Addon to invisi-ban user?

Is there an addon/mod available that will not ban a user, but essentially hide his posts from the public?

We want a user to think he's posting/not banned, but in actuality, his posts won't show up on the forum. Basically, it would be like everyone added them to an "Ignore" list.

Is there something like this out there? I've tried searching but with no luck.

Thanks!