Why do Jehovah's Witness members incriminate themselves to any judicial process?
Because they foolishly believe that the 3 elders in the room with them are there to "help" them.
They've spent years, decades maybe, assimilating that message. And in a judicial committee, they're not suddenly going to forget all that indoctrination.
Actually, in my experience, the vast majority of judicial committees are formed as a result of "confession" from a "guilty conscience", as opposed to "two witnesses" making an accusation. If people are dumb enough to confess their "sins" in the first place, why would they shut up during the trial, er, judicial committee?