While I disagree with Peter Thiel's support of Trump, I believe that he is a very smart man, and quite qualified to be a partner with YC. To fire him over his political affiliation would be petty censorship. It's easy to look at somebody like Trump and see the racist, sexist, and xenophobic parts. These attributes aren't naturally shared with Trump's supporters. As Altman said, it would be different if Thiel expressed some sort of bigotry. Also, many states (including California) have laws forbidding retaliation for political practices outside of work.
If someone working for or with YC makes or supports racist and sexist speech, it could easily lead to YC losing credibility among entrepreneurs that aren't white men (and to be fair, among white men as well). In my opinion, that could disqualify him as a partner.
