It's not, if you actually took them to court over something like this the EULA would be tossed out the window I can guarantee you that. According to Blizzard's EULA you don't even own your account it's rented out, none of this would hold up in court.
That said, I just got a permanent ban from the official forums for censored language, considering that Blizzard itself places all sorts of thinly veiled sexual innuendos in their own game this is the height of hypocrisy.