I'm not doubting what happened in your wife's situation, but it strikes me as strange that this would happen at a company where both men and women are given longer parental / bonding leave than is required by US law (and, in China, more than is required by Chinese law). The obvious reason why the company would offer this, is because it helps with employee recruitment, retention and productivity over the long term.

And, given how hard it is for large companies in the bay area to hire enough people who fit their needs, it seems irrational to let someone go for only this reason.