SWWASAS -
Yeah, definitely a conundrum. Some should be silenced by threats to their pension, etc, but not all. There should be "whistle-blowers". I don't think threats impress zealots and crusaders all that much. Whatever incentive they have to remain silent, it must come in the form of something they truly believe in, not something they're threatened with. I don't know what else it could be. It must be pretty unambiguous, pretty decisive, to have apparent total agreement.
MIB