Perm issues only if he is NOT a GPO policy member in AD.

If he is, he can FORCE a policy back even if a more experienced user were to remove it. In fact (not recommended) but he could force it to re-apply every 30 minutes if or what ever time he wanted.

If he is trying to doing it via KiXtart during logon when the user is not a LOCAL Admin, then yes... he will have issues trying to modify policies on 2000 or XP as the user won't have rights to do that.