What these clubs are frankly is an act of IRL trolling. Just like the Church of Satan itself exists primarily to troll Christians. Now you'd be right to point out that anyone who is openly trolling irl in this manner is retarded and like any troll hole it's going to attract dumbasses that don't realize it's a troll. But the modus operandi of the troll is the elicit crazy reactions from others so they can laugh at them, and they've succeeded here.

The best way to handle these satanist clubs is to ignore them. They have the legal right to operate, let them, they'll get very few participants and shut down themselves presently, especially when the participants in those clubs are shunned by larger society.