Western institution will obviously take a stance on such thing; how strong or symbolic depends on their respective relationship with China, see the incident involving former Houston Rockets GM's twitter post re Hong Kong protest two years ago. Chinese government is not going to give in to such demand from WTA. So WTA can f*** off.
But here is the problem with current Chinese political culture: Peng is obviously asked to not speak to the press or publicly comment on the affairs anymore (She is NOT under house arrest). I don't think Peng has a case in court against Zhang nor is she interested in pursuing that route. She just wanted to make a scene for Zhang by going public with such an affair. Does Chinese authority have the right to shut her up simply because it concerns about a former or current high-ranking official? If they don't shut her off, they will be under public pressure to investigate the affair. And if they investigate the affair under public pressure, it would set a precedent, which the current political culture or system can not handle. So this is always going to be Achilles heel of Chinese political system.