Let me see, is the main thrill of creating abusive usernames being that people will see them in recentchanges? Well if so consider https://bugzilla.wikimedia.org/show_bug.cgi?id=18364 "array of boring event types to exclude from recentchanges".
P.S., I tried to add the above to http://techblog.wikimedia.org/2009/04/planning-to-tighten-torblock-restricti... but it seems that is just a blackhole, and the way to reply is via this mailing list.