This is a tricky situation. While many universally agree Trump is dangerous in his opinions and viewpoints on many issues, you can't just severe ties with an investor because of their political affiliation. Thiel might be supporting a candidate with racist and bigotry views, but this is his choice. When it comes to business, you should never make things personal and I think worrying about someone's political affiliation is definitely making it personal.
Might not be the most popular opinion, but I think Sam made the right call here.