Has Jim considered "aging off" old accounts so they can't be used in this way as sleeper accounts? Automatically nuke accounts after X amount of time (and X could be a year or more). IMO, anyone who selects a screen name then doesn't use it for a year or more is simply trying to place a "back door" into the system, and should be discouraged from doing so.
BAD idea. I have friends that lurk here and don't post, but log in so they can see pings to them.