In Pachinko by Min Jin Lee, why is the old woman's death suspicious?

Question

Pachinko tells the story of several different generations of a Korean family which emigrated to Japan at the beginning of the twentieth century. The final member of the family we meet is Solomon, who gets a good job at the Tokyo branch of a British bank, and is expected to progress rapidly through the company.

His first major task is to arrange the purchase of a house. A Japanese company wishes to develop an area as a golf-course, but one property owner refuses to sell. Until she does, the whole development is stalled. Solomon and his boss discover that the owner, a 93 year old woman of Korean origin, is refusing the deal because she does not want to sell her property to Japanese people. Solomon contacts his father, who in turn contacts a slightly-shady Korean businessman, Goro, who manages to buy the property from the woman. He then re-sells it to the Japanese client, and it looks as though the problem is resolved. However, a few days later the old lady dies:

Matsuda-san, the old lady, is dead, and it doesn’t look good. When the client wanted the property, he didn’t expect that the holdout seller would die a few days afterwards.”

“How did she die?”

“Not sure. It could have been a heart attack or a stroke. They don’t know... But the facts remain that there is a dead woman who didn’t want to sell her property. Everyone knew she wouldn’t sell, and moments after she sold, she died.”

Because the clients don't want a "run in with the yaks" they put the project on hold, and Solomon is fired.

It certainly appears probable that Goro is connected to organised crime. But why is the death assumed to be suspicious? The lady was 93 years old, after all. I can certainly understand that she could have been threatened into selling, and if she was stubborn they may have killed her in the hope that her heirs would be more reasonable. But what would killing her after the sale was concluded achieve? It seems to just draw unnecessary attention to the deal.

Answer 1

After mulling over this question I've come to three different hypotheses.

The first possibility is that Solomon's boss, Kazu, is lying, and that the old lady's death was in fact of natural causes and nobody was bothered or surprised by it. We are not provided any independent source of information about the client's state of mind except from what Kazu says. But in this way he has a pretext for firing Solomon after he has served his usefulness. This fits with the general theme of the book, of the Japanese just making use of Koreans to do their dirty work, and then discarding them when they are no longer of use.

The second is that the old lady was still reluctant to sell, even to Koreans, and Goro used physical intimidation to change her mind. She was a frail old woman, and if she was roughed up by thugs it is certainly possible she would die a few days later.

A third possibility, suggested by Rand al'Thor in comments, was that there was a breakdown of communication between Goro and his operatives, and she was killed by mistake (maybe a Thomas Becket-type situation).

On the whole I tend towards the first possibility, as if fits with Kazu cosying up to Solomon in the weeks before the sale, when he saw that he could use him, and then cutting him off completely afterwards. But in the absence of any comment by the author, I think this can only remain supposition.