Sorry, my intentions were not to lock this, so I'm not sure how it happened.
Needless to say I am currently unsure of what the policy is on nickname changes, though I have done it for a few people in the past. Right now (pending a request in PM right now). I am going to discuss the matter with Hal and he, or I will give the result on the matter. I feel its unfair to restrict people the ability to change their user names, however it could be very problematic. I think if a user requests it, it should be granted on denied on some sort of basis.
Again, sorry for the lock, I was meaning to answer the question.