My opinion: The people that bailed on Peter Thiel would have been potential flighty partners for other reasons later on. If someone can't abide by a business partner having a different political view then that could indicate a rather rigid mindset - and given the fluid nature of business, that could become a liability at some point in future.
There is a big difference between a different political view and the words and actions of Donald Trump. If it was Romney or Cruz or Rubio or almost anyone else I don't think you'd see any of this happen.
That said, Peter Thiel has said and done offensive things in the past on many occasions. Support of a Trump candidacy should not be surprising for someone who has said that women's right to vote is a threat to democracy, or who would bankrupt a company to retaliate for an employee outing him. I'm happy to see Thiel start to have repercussions for his actions, but the same tech community that forced Brendan Eich out of a job for a $1000 political donation has taken years to start forcibly taking a stand against Peter Thiel. Clearly, Thiel has tons of money and business acumen, which a lot of people want more than to "do the right thing". I imagine all of this -- if it is significant at all -- dies down after the election anyway.