I'm aware of that legally the distinction is relevant, but in the realm of public discourse, it isn't. YC could also e.g. cut ties with Thiel because he's gay, but of course HN would crucify them.
Sorry, I still disagree. As an alternate example, if I heard that a business partner had decided to stop doing business with another business partner because of disagreeing with their politics, that would play very differently in the press than a boss deciding to fire an employee for same.
He doesn't even "do business" with them! As Altman himself said: Thiel doesn't get YC equity. It's a marketing relationship. If it were an employment relationship, I would probably feel differently.
I think it's pretty relevant that Thiel isn't an employee of YC. Saying that they would "fire" Thiel is a complete misnomer - he's a partner that does business with them. I think that's a very different kind of relationship.