People put on a false front with offensive messaging claiming support of these groups, but the whole purpose is to build clout or benefit themselves. They don't care about the message at all.
Messages like "I support lgbtq, and if you don't you're a bigot," are self-aggrandizement. "I support lgbtq," is all that's needed if you want people to know they are supported. No one needs to hear it at all if the discussion isn't relevant. Just try to treat everybody with respect.