When I tried cd's exercise my elbows and hands didn't move at all until my hips had rotated about 40*, and at that point the hips could rotate no more without taking the torso and shoulders along with them which of course also then moved the elbows and hands.

So, I agree that at ground level (when the arma and hands are fully extended down) the hips or legs can slowly move the arms and hands by dragging them through impact. The question then becomes can the legs and/or hips move the arms/hand/club down from their elevated position at the top of the backswing, and also can the legs/hips move fast enough at impact to drag a 100 mph clubhead through impact? I would say no to both parts of the question. At 100 mph the clubhead is traveling 145 feet per second or roughly 2 revolutions per second around its arc. In order to be dragged at impact by the hips, the hips would have to be spinning faster than 2 revolutions per second. Not possible unless perhaps you are an Olympic ice skater or a ballet dancer who is spinning off their feet with their hands and arms withdrawn into themselves but definitely not with a golf club extended away from them.

Tom