I'm sorry, if you are like "I'm glad they gave me the money and the label" and can't take it when someone associated makes an embarassing human moment, you are just trying to have your cake and eat it too. Do better.
YC can have political opinions, but they should acknowledge the opportunity cost of putting their politics before their community. Behavior like the one linked in the OP is incredibly petty and probably should make the associated parties feel bad about working with that kind of person. Lord knows I feel ashamed to be an HN user today.
Free speech has consequences. And speech that has unhinged threats (even if it has a disclaimer that it's not) has potential consequences with law enforcement.
I don't think it's out of line for someone who's investing their time and effort into an organization to be critical of leadership.
I'd argue you have reached the limits of free speach the moment there are consequences for just the speech.