No it isn't. Discriminating against certain classes of people is illegal. It's perfectly legal to discriminate against individuals based on their behavior.
Would it be ok if a company didn't care that a user is gay or not, but they hated that he celebrated gay activities? Even straight people celebrate gay pride and rights. Can we discriminate against them? Seems pretty similar.
No it isn't. Discriminating against certain classes of people is illegal. It's perfectly legal to discriminate against individuals based on their behavior.