I don't know, I suppose I picture you joining chat and getting into some sort of argument with someone where you call them hitler, at which point you realize that hitler is a censored word and at which point, they realize they'd like to report you. So you get reported, admin comes along and decides he doesn't want to deal with your shit and bans you. Often times, people get banned not because of 1 single thing, but because several things came together at the same time.
The assumption here, on my part, (but it is a safe one) is that Blizzard isn't watching every name that beats the filter. They are taking action when one of your peers reports your name.