I'm not sure how many new registered accounts happen here daily, but if they are < 5 it's often easier to ban a member and disable new registrations temporarily (or with moderation approval). This prevents any of that from happening immediately afterward or however long you need like a 24hr period. That setting is underused in forums, it can save you grief.
Also, thanks for that I'd be happy to help if you expand the staff again in the future.