Why bother with censorship in character names, when the media screws up kids much more and theres nothing you can do about that?
I played with 13-year olds on this game who said more bad words in an hour than I say in a week
That's how messed up they already are ^^
I'd say: leave it uncensored and ignore people with bad names.
Put in censorship and they will search for way to have a crappy name anyway (e.g. f|_|ck or using '@' in stead of 'a').
Ignoring those with lousy names or telling them they need to change their name and then ignoring them, will have a better effect.
The silent treatment this would be called. It only affects the people with bad manners.