Walter, I have no reason to doubt that "the equipment" as you describe it exists and is accomodated into the Chinook with the ease and speed with which you tell us. But I'm afraid that caz is quite right you know, if the scenario that you describe had occurred then the RO's finding effectively stands (not withstanding that it was itself in contravention of RAF regulations). Both JP and you have come to variations of the same lack of airmanship. He proposes that they miscalculated their position such that a "cowboy" climb into IMC caused them to crash instead of clearing the hilltop, and you propose that they miscalculated their position by putting all their faith into "the equipment" before making a "cowboy" high speed approach into an IMC obscured LZ, causing them to crash. Whoever the person might be with the handheld gizmo and wherever he was and regardless of his intent, the responsibility for making such an approach lay solely with one person, the aircraft captain. Someone more qualified than I in SH Ops should really respond, but that's my take and my attempt to answer your question:
What have you got to lose?
Everything, I would suggest.