Is it a good idea to let users have the name '
As sepp2k said, this has already been brought up on SO. There's no rules on avatar names, and there isn't any trolling or impersonation here. The official verdict seems to be:
AFAIK there is no official policy on user names, and the only one on avatars is that they should be PG-rated (i.e., nothing offensive).
Users on SO aren't allowed to solicit other users, so if a fake Jon Skeet were trying to pull a con on another user in order to get something, that would be reason enough for action.
Same goes if they were impersonating for the purpose of trolling. Trolling isn't acceptable here, so they can be dealt with.
So, there is no problem with this username.