Allow admin to change a user's name
Administration -> Manage Users -> Select a user to see their details.
Display the user's name on the User Detail page (so admin can see it) and allow admin to change it (in case of inappropriateness or similar)
Of course admins should only be changing other people's data very rarely. In most cases, I suspect it would be more appropriate to disable/hide offensive accounts with offensive names (but in such a way that the user can still log in to fix them) - or perhaps it would be simplest just to hide the offensive name.