Everyone that knows about Peter Thiel knows he's an outspoken libertarian, critic of the GOP and DNC, and that's he's homosexual. The surprise isn't that he's not a Democrat (everyone knew that) it's that Trump isn't exactly the libertarian on...any issue (at least not openly.) There is the assumption that Trump will be a major disruption to the establishment, that I have seen some libertarians and liberals both embrace.
I have a hard time believing Thiel actually embraces Trump, and it's more that he was going to be a delegate and will now be legally bound to cast his first ballot for Trump. I am frankly a fan of Thiel, a lot of people here at HN love Musk but I think Musk is a corporate welfare queen; and Thiel is not.