well, they're in control of THEIR servers. and the ones they admin.
oh, and, don't mind people who say that they can ban you from all of blockland. remember they have NO POWER over banning you globally, just locally. they're trying to scare you into doing whatever they need you to do.
also there are no rules on blockland. you know, at least globally. the forums have them, individual servers have their own rules, but nothing is enforced game-wide, so when one server is going on about you can't cuss, another server will probably not have that rule.