Firstly in honour of Star Wars "It's a trap." Anytime one shoulder is turning back you've got one turning foward. Whatever the call is should be the same for both.
2nd players are allowed to twist,turn, move backwards to protect themselves. If they have lgp and any movements within their cylinder are simply to protect themselves I,be got no problem. PC both times.
Now if the turn and dip their lead shoulder not to protect but to deliver a blow and lean forward beyond their space or a similar situation it would be a different story.