Presumably this person had already run the gauntlet to become an admin. Thus, being able to do that is no guarantee that a person will not turn rogue. It also shows that when it does happen the community has effective and efficient techniques for coping with this. It's something that the supporters of the current RfA system should keep in mind.
No reasonable person would ever claim RFA to be perfect at stopping rogue admins. We always knew there was a chance of an admin going rogue, the idea has always been to minimise that risk (without unreasonably withholding admin tools from anyone), not eliminate it. As far as I know, this is the first instance of an admin going rogue in this way - 1 out of about 1200 is pretty good going if you ask me.
And, of course, I congratulate those members of the community who dealt with the issue in exactly the way we've always said it would be dealt with - well done!