Jim, that sounds like the most plausible reasoning. As with many things in golf, the final decision is left up to the integrity of the player. Did he try to stop and lost the club? Or, was he swinging through... the club slipped out of his hands at the low spot in his backswing, moving the ball into an unplayable position? I guess I can't see the club continuing into the dirt right behind the ball if the player attempted to stop his swing. I can, OTOH, see the club slipping out of his hands as he is swinging through the ball. This should be no different than someone playing 10 year old grips that are slicker than waxed linoleum. The player has to decide/state whether or not he attempted to stop his swing BEFORE the clubhead arrived at the ball.