Well, ok then. Except... in that particular case schizophrenic people usually have a poor sense of reality, heck even words like "hellban" and "dead" may have religious connotations. Not really sure what a better solution is.
You don't seem to know much about the Terry Davis situation. When a persons posts are 50% racist slurs, there isn't much choice but to block them from posting.
The hellban lets that person still post and converse with people who actively seek him out, without the downsides of having tons of hate speech all over the front page of HN.
It's been said before and it'll be said again, schizophrenia is not a catch-all excuse for someone in a public forum.
I just feel bad for the guy. Originally, I was just pointing out it was a kind of censorship greater than downvoting that has some unsavory aspects to it. Like I wrote above, it's not clear what a better solution would be, except perhaps if I was running things I would try just deleting his accounts. Oh, and you can't reply to his posts, but whatever.
Deleting accounts will cause him to create new accounts. The positive of a hellban is that it lets the person still use their account to broadcast to those who explicitly want to hear it, so there's much less reason for the person to make a new one.
Being temporarily banned from an online forum is probably pretty low on the list of shitty things that happen to people with a diagnosis of a severe and enduring mental illness.
Some people know they're hellbanned and post anyway.