Hmm, funny that the old Traitor King hero has been disabled. That sounds suspiciously like a statfix bug wrt national unit lists. I know for a fact that there is only one traitor prince unit type in the game and that one costs gold and is a recruitable commander.
Likely I have accidentally replaced the old traitor king with the traitor prince while adding heroes in dom3. Heroes are added in a new nationdata now that wasn't there in dom2.