I am aware that currently legally it is the exact opposite and they have no responsibility to save or protect anyone only themselves.
And, pray tell, who in their right mind is going to take _that_ job?
Hopefully this would change the public's perception of police to some extent and improve public relations to the point that they would walk around being thanked like veterans.
I've just gone through the information at https://www.odmp.org/ for the last 3 years and I can't find an example of anything like this.
You are completely correct that it's largely a fantasy scenario, but who wants to take the chance?
Gun training is if you shoot someone you shoot to kill. Wounding just gives them a chance to shoot you back. This is universal, ask any officer trained to use a gun and they'll tell you that shooting the gun out of someone's hand is Hollywood nonsense. Shooting to wound leads to accidental death (hit the femoral artery) and/or retaliation.