The upside here is that you can blacklist based on some identifiable information as long as it can be easily confirmed. I dealt with quite a few mentally ill a

The upside here is that you can blacklist based on some identifiable information as long as it can be easily confirmed. I dealt with quite a few mentally ill antagonists when moderating Quora. The best thing to do though is to let them use your service, but to shadow ban them as much as possible, and ideally make them think they aren't. Feel free to contact me if you want to chat further.