Oh. Maybe he was just removed from the visible list when you click on the "staff" button but not yet had his powers removed? Maybe it's just a mistake or coincidence or whatever. As the old saying goes, never assume malice when good ol' ineffectiveness suffices.
It's still annoying. I'm assuming to takes something like one or two clicks to change a user from an admin to a regular user, pretty much as easy as it is to remove someone from the admin page, and it still hasn't been addressed?