Good point, maybe we need Cyrus or Theymos to clarify this.
There was a exclusion test once, but I don't want to say who was participating in it, and 2 DT1 exclusions of another DT1 member did absolutely nothing. Therefore, it was always my belief that DT1 members can never kick out another DT1 member. IMO ask theymos.
Then that would kill off the "self policing" theory and toss it back to Theymos.