its a feint and a slipping motion.
its a feint because it makes your back shoulder move.
when your right hand is starting to come out your back shoulder moves in the same way so whenever you show this feint you create an image that your right hand is starting to come out.
and its a slipping motion because it makes your head move.
makes your head hard to pin point on the way in so you dont walk head first into punches when you come forward.
but the main thing is that by being a slipping motion your head isnt just harder to pin point there are many different counters you can throw using the same motion too so just by showing it you can make guys very tentative to throw any punches from a fear of being countered. thats why aggressive boxers come in with head movement.
yeah and i think he was tentative too. he really needs to maintain a nice workrate for his style to work the way he wants it to. but i dont think he wanted to be dragged into a war against a guy that is always ready to take a shot to give a shot and he was holding a lot which decreased his workrate even more. really bad style. but its one you are going to see much more in the pros.