in a very short summary IIRC it was because he made a stupid joke on a feminist holiday and that combined with the fact he was more libertarian politically (despite being fairly socially liberal) made him equal to Hitler in the eyes of the woke mob
they proceeded to work to get him fired from Kinda Funny (which ruined one of his closest friendships because Greg has cruelly cut Colin completely out of his life over it) and the mob absolutely loathes that Colin then struck out on his own (the fact he did so successfully makes them even madder)