To be fair there's whole areas of law that are less well-defined than a goth in a blackout...
Look at the Hunting Act 2004 frinstance. While it specifically bans the use of hunting with dogs, getting a prosecution is incredibly difficult - you virtually have to be there with a camera at the kill - so police forces that are less in the pocket of the landowners are now going for variations on Community Protection Orders; everyone knows the hunt is still hunting, most want it stopped so the only way of attempting to do that is via a seriously around-the-houses sort of way.
Similarly, government are fed up with JSO protestors so they (and councils, companies etc) are taking out injunctions to stop them standing in certain areas on pain of prosecution. And they have been prosecuted, on a number of occasions!
For quite some time, women in this country have had the right to have an abortion and they've been intimidated and harassed by anti-abortion activists. Therefore, in order for these women to go about their perfectly legal business without fear of harassment or even the threat of violence, government has introduced effectively protest exclusion zones. So if matey is protesting outside said clinic, despite him calling it praying, it's still a protest that's not allowed there. He's still standing there in a way that vulnerable women would see as intimidating... It's not really a thought-crime as such because he's allowed to think whatever thoughts he likes, just not to stand there making it obvious he's protesting!
Meanwhile 😁