If Thiel was getting into bed with this guy, then yea, you can probably impute some knowledge b/c Thiel would do some diligence. But we are talking about a dinner and an email.
I met a new person this weekend under similar circumstances. You shouldn't take that as a a sign I agree with that person's politics.
Personally, I would be open to such an experience. I am not so insecure in my beliefs that I would worry on that front. I might learn something about them and the nature of the world, and maybe they would too.
Maybe this will sound corny, and I guess it probably won't land with non-Christians, but I'll offer my heuristic anyway: What would Jesus do? I don't think shunning is the answer.
I know nothing about Thiel, but the actual quote is "hosted a dinner with" which like the one you responded to here said, could easily mean there were 50 guests at a party and one of them was this guy.
Your made up quote is something entirely different.