He didn't file a frivolous lawsuit. He decided to not file a frivolous lawsuit, and instead to fund every viable lawsuit he could purely so he could bankrupt a media company that had covered him very unfavourably in the past. He'll probably keep doing it, if more such cases pop up.

He isn't on Hulk Hogan's side. He's on his side, and he won. Making this about the particulars of Hogan's case is deliberately eliding the fact that Thiel didn't give a shit about Hogan's case other than that it could bankrupt Gawker.