I have seen right handed pitchers not stop several times in the Major Leagues with a runner on first.
Everything else about their body is stopped and still, except that their hands just come and bounce before they pitch.
I know the base stealer's trying to get their lead can see the pitcher isn't stopping with their x-ray vision looking through his back.
Know what I'm saying.....?
I think this is the philosophy about not calling it. But who knows!