Or the admins could just reserve hellbanning for only the most persistent serious trolls. It is a useful tool but should only be used in extreme circumstances, not just for one bad comment. If it was used only once a month or every few months for persistent trolls it wouldn't be a problem.

Bad comments get voted down anyway, so there's already a mechanism for that, IMHO hellbanning should really only be used on people trying to post spam repeatedly or repetitively troll comment threads.