After he did his AMA on reddit he took a look around and stated something along the lines of it having "too much of the bad internet" and didn't stick around.
Also he's Canadian and not from the Prairies, so unlikely to be alt-right. His biggest flaw I've heard of in a few places is that he "works to rule" in the union sense. He does things that make him money WRT his fandom and his acting.
E.g. the big fallout he had with George Takei was because in his eyes, Takei as a person would benefit more from Sulu staying on the Enterprise and playing more in the movie, because more screen time equals more cash.
Takei took the minor role because it made sense for Sulu as a character, as well as personally the representation of a Japanese (and then closeted gay man) as the captain of a starship.