https://web.archive.org/web/20200309104931/https://www.newyorker.com/magazine/2006/08/28/manifold-destiny

This new Yorker article goes into some more detail. Apparently there was an underlying conflict between rival Chinese academics over succession of university admin postings in Beijing.

According to the article it was one Chinese dude trying to hog credit and Perelman basically went "oh i'm not brave enough for politics" and bailed. If he accepted his choice was basically becoming a conformist or getting involved by trying to improve things. He chose not to choose.

Most problems require the insights of several mathematicians in order to be solved, and the profession has evolved a standard for crediting individual contributions that is as stringent as the rules governing math itself. As Perelman put it, “If everyone is honest, it is natural to share ideas.” Many mathematicians view Yau’s conduct over the Poincaré as a violation of this basic ethic, and worry about the damage it has caused the profession. “Politics, power, and control have no legitimate role in our community, and they threaten the integrity of our field,” Phillip Griffiths said.

p.s. Also between some behavioral tics (very picky eater, refusing to trim nails, trouble socializing) and the elevated sense of justice I nominate him as an honorary autist. we stan