Just going to add that jokes are really only considered acceptable if the person targeted by the joke is okay with the joke being made. So writing it off as "just a joke" is missing the point - the person targeted by the joke has to be okay with it being made. Allowing jokes to be made at others' expense without their approval is opening the door to all kinds of nonsense the staff don't want to allow. And really, I can't blame them.
Now, if a member without any history made a joking comment to "shut up" which didn't go over well with the target, they'd probably just get a verbal warning. But Channy had several active warnings already, ergo b& for two weeks. Mumble's next fuckup will get him two weeks as well.