When you start moving a bit a few things happen. You breathe better which calms the psyche a bit. You open up what all you can see- that 2nd guy that the first was baiting you towards. And it opens up escape routes and/or avenues of attack/flank to you. It also puts you on the initiative and changes the dynamic a bit.
Every time I teach knife or pistol disarms, I try to emphasive the movement first. If you teach hands on right off the bat, movement literally stops. But often if you teach movement first and then the hands on, people will more naturally keep the movement as part of it.
Just like when you put a gun in someone’s hand and they go stiff and their movement almost becomes robotic. They have focused too little on the movement and too much on the gun. You have to balance it.