Well, what if Thiel supports David Duke or comes out as a holocaust denier -- would you still claim that Thiel's professional career can't be at stake?
There's a difference between David Duke and a mainstream party candidate supported by roughly 40% of the American population.
First, Trump is supported by roughly 40% of likely voters, not all Americans. Second, just because a belief is widely held doesn't automatically make it more acceptable than it would be if it were less common.
In the July 1932 German Federal Election, the National Socialist German Workers Party received 37.3% of the vote. [1]