They are also not swallowing when they strike and they can open their mouths to just about 180 degrees if not all the way to 180 degrees. They can bite your big calf or thigh if they wish so there is no need for this during a strike having felt I've seen enough to know. And the can strike anywhere on the prey not just the head but irrelavent due to that the head is the smallest place on a prey items body. So I still see no sense In that arguement.
Plus there is a reason snakes eat prey head first. Yes a skull does not give as a stomach does but I have never seen a snake struggle to swallow the head of a prey item. If anything it is the easiest part the jaw doesn't even fully expand until it reaches the body.