I notice the player has his right hand there, just in case he needs it. He can get the full benefit of right-hand-less playing while still having his right hand. In fact there is absolutely no difference in his enjoyment of playing the left-handed piece even though he has his right hand in standby. He may at some future point have a desire to use his right hand for some unforeseen circumstance and then he'll be glad he kept it attached. Good point.