You're right, I would have supported their action. It's not a double standard though, because they were denied service on illegal grounds by people attempting to foist their religion on others.
In this case, we once again have a gay person quietly selling his own wares, when suddenly a particular group of Christians feel the need to stick their nose in. Nobody is being denied service, nobody is breaking the law, nobody is infringing on anyone else. It's just one group acting like a bunch of theocratic bullies.
Naomi, all your argument really comes down to in either case is, "I don't like it." You don't seem to like that Christian B&B owners are not allowed to refuse gay people service when they have already made arrangements to stay with them, and you don't happen to like this artist's trinkets. Sorry, not good enough.