Attack the argument, not the person. Anything less demonstrates the weakness of your own idea.
The problem Ms. Pao is that you’ve not bothered to explain how Mr. Thiel’s argument is weak or wrong. Instead you’re attacking an argument that he never made.
His argument isn’t that his support is based on the exclusionary policies of Mr. Trump, but that it is based on demanding an outsider change the way Washington functions. So your counterargument would be to explain why he should abandon that overarching goal, because the exclusionary policies are more important than outsider shakeup. Not simply that the candidate is flawed therefore as an ardent supporter you must be as well. To support a candidate is not to agree with them on every policy, that’s the challenge for representative democracy.