This is a strange question for a number of reasons. First of all, it's quite broad and meandering. There's a lot of assumptions in the question that aren't correct and need to be corrected. I mention this as way of explaining and apologizing for the meandering style of this answer.
The central character is a reimagining of Shakespeare's Caliban, a Caribbean black man who finds white women to turn him into whatever they want him to be. For some reason, it seems only white women ("golden girls", as he calls them) will do:
(It's actually quite common to use blond hair as a symbol of whiteness -- even the dictionary definition of blond mentions pale skin and dictionaries aren't great for this kind of task -- but I digress).
The story actually is a lot more specific than this. In fact, the funny thing is in this question, you quoted from a paragraph that went into a lot of detail, but you ended the quote before the detail began. Let's take a look at the first quote, the one about Miranda, but let's read the full paragraph -- not the first few sentences.
Once, after the touch of other pale lips, you looked into the eyes of a golden girl, one Miranda, and saw yourself reflected back in her moist, breathless stare. In her eyes you were tall, handsome, your shoulders powerful and your jaw square. You carried yourself with the arrogance of a prince. You held a spear in one hand. The spotted, tawny pelt of an animal that had never existed was knotted around your waist. You wore something’s teeth on a string around your neck, and you spoke in grunts, imperious. In her eyes, your bright copper skin was dark and loamy as cocoa. She had sighed and leapt upon you, kissing and biting, begging to be taken. You had let her have what she wanted. When her father stumbled upon the two of you writhing on the ground, she had leapt to her feet and changed you again; called you monster, attacker. She’d clasped her bodice closed with one hand, carefully leaving bare enough pitiful juddering bosom to spark a father’s ire. She’d looked at you regretfully, sobbed crocodile tears, and spoken the lies that had made you her father’s slave for an interminable length of years.
This is something that's a lot more specific than "turn him into whatever they want him to be". Miranda sees Caliban as a exotic racial stereotype (spears, necklaces with bones, wearing furs are standard stereotypes about people from Africa, and Hopkinson even goes as far to clue us into the stereotype isn't real ["an animal that had never existed"]). She finds the stereotype sexually attractive and they have sex. When the father arrives and sees them, Miranda claims that she was raped, and Caliban gets in trouble -- relevant article.
And here's another example of a white woman "turn[ing] him into whatever they want him to be":
Ariel sniggers. “That was from his last ooman,” she says. “The two of them always quarrelling. For her, Caliban had a poison tongue.”
“And spat out biting words, no doubt,” Sycorax says. “He became what she saw, and it affected the children they made. Of course she didn’t want them, of course she left; so Grannie gets to do the honours. He has brought me frog children and dog children, baby mack daddies and crack babies. Brings his offspring to me, then runs away again. And I’m getting tired of it.” Sycorax’s shawl whirls itself up into a waterspout. “And I’m more than tired of his sister’s tale tattling.”
The clue here is that "crack babies" are racist stereotypes, a mac daddy is a pimp so "baby mack daddies" essentially means that the child is predisposed towards crime (another racist stereotype), and frog children and dog children plays on the idea that people who aren't white aren't really human. So while "turn him into whatever they want him to be" is the language the story uses, for the purposes of interpreting the story a good way of reading this is white women see Caliban as racial stereotypes.
Why is Caliban only interested in white women? It could be just his taste in women, but I'm sure there's some deeper significance, given the underlying racial tensions hinted at throughout the story.
This is a strange way of approaching the story. You're trying to create a difference "dating" (is this "just his taste in women") and not-"dating" ("deeper significance"). The phrase "deeper significance" implies a view of literature where (to use a tired example) one reads "the curtains are blue", interprets this as "this symbolizes the characters' depression", and this knowledge is the "deeper meaning". However, I can assure you that while the people in this story aren't real, the experiences the story describes absolutely are real. By this I mean that there are real people who have the same "interest in white women" for the exact same reasons Caliban does. The "deeper meaning" to be found here is the task of understanding real people in real world situations.
It's worth mentioning that while you separate "racial tensions" and "one's taste in women", there have been more "racial tensions" associated with dating than I could possible keep track of. "Racial tensions" associated with dating are not "unusual", as you claim in a (now deleted) comment. It wasn't too long ago that there laws about who could date who and who could marry who, and today people get hashtags like #SiMaFilleRameneUnNoir trending on twitter. I've read more articles (you can google "colorism dating" for a small taste) and heard more stories about racism related to dating than I can keep track of. This point is relevant because the entire story meets your definition of "racial tensions" associated with "one's taste in women", and the underlying context -- that the story isn't an allegory but describes real people, and that the real people described aren't few and far between but actually quite common -- is quite important.
Finally, the "racial tension" in this story is not "hinted at". I recognize that there is cultural knowledge that not everyone possesses, and I'm not trying to blame people for not possessing this knowledge, but assuming familiarity with something is not the same as hinting. Relative to other writing about race, this story is actually quite direct. The cultural knowledge related to race necessary for this story is much less obscure than the cultural knowledge needed to understand, for example, the references to The Tempest.
You ask "Why is Caliban only interested in white women?" In the story, Ariel asks Caliban the same question ("Why you can’t leave white woman alone? You don’t see what them do to you?"): let's see what the response is:
“You are our mother’s creature,” you hiss at her. “Look at you, trying so hard to be ‘island,’ talking like you just come off the boat.” In your anger, your speech slips into the same rhythms as hers.
This might seem unrelated to the question but actually it's not. Ariel and Caliban are talking about patterns of speech -- they're contrasting the vernacular of their culture ("talking like you just come off the boat") with the more formal speech of the white colonizers ("chat like something out of some Englishman book.") Caliban is essentially making fun of Ariel for refusing to assimilate to the white colonial regime ("Look at you, trying so hard to be ‘island,’"). Since this is his response to Ariel's question of "Why you can’t leave white woman alone?," he's essentially saying that he's trying to become part of the regime. There's an interesting detail where Caliban reveals he can't truly assimilate -- no matter how hard he tries, his "speech slips into the same rhythms as hers."
There's several passages that go into much more detail. For example, here's some insight into Caliban's character from Ariel
Caliban have a sickness. Is a sickness any of you could get. In him it manifest as a weakness; a weakness for cream. He fancy himself a prince of Africa, a mannish Cleopatra, bathing in mother’s milk. Him believe say it would make him pretty. Him never had mirrors to look in, and with the mother we had, the surface of the sea never calm enough that him could see him face in it. Him would never believe me say that him pretty already. Him fancy if cream would only touch him, if him could only submerge himself entirely in it, it would redeem him.
Cleopatra allegedly bathed herself in milk to keep her skin pale, so Ariel is essentially saying that Caliban wants to become white (i.e. be "a mannish Cleopatra"). Ariel also reveals that Caliban thinks he's ugly because of his race: Caliban believes "if cream would only touch him, if him could only submerge himself entirely in it" like Cleopatra, then he would no longer think so poorly about himself and his body. The story uses bathing in milk, but actually skin lightening is a huge industry (here's an article about this that specifically focuses on Jamaica).
You're probably wondering why all of this leads to Caliban's desire for white women. The very idea of race is that its passed down through descent. This is stated relatively clearly in the story (a bit of symbolic language but a lot easier than the tempest references -- I mention this not to blame you but to emphasize that the "racial tensions" are not "hinted at" in this story):
There was a time they called porridge “gruel.” A time when you lived in castle moats and fetched beautiful golden balls for beautiful golden girls. When the fetching was a game, and you knew yourself to be lord of the land and the veins of water that ran through it, and you could graciously allow petty kings to build their palaces on the land, in which to raise up their avid young daughters.
To break it down: "you" (i.e. Caliban) was the original inhabitant of a land (i.e. "lord of the land and the veins of water that ran through it"), and white people colonized the land ("you could graciously allow petty kings to build their palaces on the land"). What happens next? The white people "raise up their avid young daughters," i.e. they raise children, and their children are turned into adults and raise children, and the whole thing perpetuates itself. This is why it's a big deal when Miranda's father catches Caliban with Miranda: by having sex with Caliban Miranda is breaking the cycle.
The white women sleep with Caliban because they find their stereotypes about him to be sexually arousing ("The spotted, tawny pelt of an animal that had never existed was knotted around your waist," etc.). Caliban sleeps with the white women because he desperately wants to be included in whiteness, in that cycle of social reproduction that defines what whiteness is. He's internalized the racist myth that black people are ugly, and white people have the power to turn him into things he's not (again, "The spotted, tawny pelt of an animal that had never existed was knotted around your waist," etc.). Unfortunately, the white women see him as dehumanizing stereotypes, and that's all they can ever see him as.
You haven’t seen yourself in this one’s eyes yet. You need her to kiss you, to change you, to hide you from your dam. That’s what you’ve always needed. You are always awed by the ones who can work this magic. You could love one of them forever and a day. You just have to find the right one.
Caliban wants to find "the right one", the one who can turn him into "a mannish Cleopatra" by seeing him as white and including him in the social reproduction that defines whiteness. The problem is the right one doesn't exist.
It's worth mentioning again that this isn't an allegory: the story describes real people even though the characters are fictional.