I think the problem here is that the only type of banning you have is hellbanning and slowbanning. It would have been clearer if you had just “normal-banned” jcs, so he got a message saying “you have been banned and can’t post anything”. That would have avoided the misunderstanding to some extent.
Hellbanning should be reserved for users you want to prevent from noticing that they’re banned, so they won’t create a new account. That would be users who you think hold no hope of salvation, not those who you are just giving a warning to.
Even better in this particular case would be yet another type of ban that informs the user “you have been temporarily suspended from posting; check your email for the reason”. That would let the user know that the ban is temporary so they don’t get upset that they were apparently permanently banned for one mistake.
Yes, it would be nice feature to have two kinds of banning. But there are so many other things on my todo list, and though this particular glitch attracted lots of attention, it happens vanishingly rarely and doesn't affect the site much. So there is a lot more payoff for users if I focus on e.g. ways to improve comment threads.
Hellbanning should be reserved for users you want to prevent from noticing that they’re banned, so they won’t create a new account. That would be users who you think hold no hope of salvation, not those who you are just giving a warning to.
Even better in this particular case would be yet another type of ban that informs the user “you have been temporarily suspended from posting; check your email for the reason”. That would let the user know that the ban is temporary so they don’t get upset that they were apparently permanently banned for one mistake.