He did his due diligence when he ported her over, making sure she couldn't access menus, and therefore be unable to log out.

He also covered everyone who is now a disembodied brain in a steel case.

What he didn't account for when they ported the data from SAO was that any of the traumatized players who were released would come right back to similar games, and have the same username. Or at least that's what I would guess.