Even if it's a design flaw you should take care with who is allowed to promote/demote and change hierarchy settings.

Also i'm sure you've been robbed by a player not an RMT, RMT sellers and spammers have something in common, original names from stolen accounts, randomly generated names (those follow lore naming conventions), names containing the name of the RMT web page or names that contains "sdf", i would get rid of that "leader" you got with the merge.