I think a lot of the comparisons of Twitter to bakeries miss one important point. Trump didn't want cake, he wanted a cake with messages promoting violence written on it. The homophobic cake shop wanted to deny all cake to the gay couple. Trump wants the Twitter bakery to send out cakes piped with an offensive message that goes against their moral beliefs. Twitter isn't denying Trump service because of who he is, or even what he believes, they're denying him service because they don't want to actively help him spread a message that promotes violence.