As David says above, the definition of cabal is any group of which the person crying cabal is not a member.
The list was set up because a conversation between a number of people in a cc list was causing occasional dropped messages (because people hit reply not reply all) and because it did seem that there was a problem that wanted talking about.
If you want to ban all discussion of Wikipedians in any forum other than Wikipedia then you will have to shut down IRC, this list, arbcom-l, and probably the "email this user" feature as well. It is in the nature of people that they wish to explore things. It is also obviously the case that people might say things privately that they would not say publicly, for any one of a number of reasons. That does not mean that any such statement is a statement of intent, rather than, say, a shout of frustration.
Do you honestly think that members of the arbitration committee would collude in the blocking of Wikipedians who had done nothing wrong? That is,. essentially, what is being suggested here. I find it pretty incredible as an assertion.
Guy (JzG)