I'm not sure why that quote that people keep bringing up is so outrageous to people. In my opinion, it's a pretty factual analysis of the political climate; in which the voter demographics have shifted in a way which makes it tough for libertarians to win elections. Welfare recipients, for obvious reasons, are anti-libertarian. Women, supposedly, are also less libertarian than men? I don't know if that's true; but regardless, what's wrong with stating that fact.
I think people are upset because they assume that it's implied in Thiel's statement that he believes women shouldn't have received the right to vote. But it's important to note that he has never advocated for that. Not in this quote, anyways. He was merely pointing out a few shifts in the past century that have made it extremely hard for libertarians to win elections.