I get it’s a harder problem to restrict who tickets are sold to, but if a venue like that wants to get petty about who can attend their shows then the responsibility is on them to communicate that before the event.
To flip this another way, in any other normal circumstance, when you get banned from a venue you’d get a very clear communication telling you so. There is no ambiguity, you know you’re banned. Yet here the venue is still happy to take peoples money but doesn’t want to admit them. They’re basically having the best of both worlds.