I never liked the idea of shadow ban myself, which is why I wanted to make it a plugin and not core. And even the client that commissioned it had lots of problems with their users eventually finding out they were shadowbanned. The fact that they're not around now anymore may give you an idea of that.
I'd like to advise against it, it's not the best policy in the world, but if somebody would like to pay for us to upgrade it (probably 1-2 hours worth, including support for the next couple of minor versions of NodeBB) then, sure.
