I would think that a basic tenet of a rational use of deadly force would be to prevent further violence to self or the public. A high speed chase puts everybody in it's path at risk. The peace officers in pursuit are demanding that the speeding vehicle stop, lights, siren, etc. Most pursuits start as a less threatening situation that the pursued driver wishes to avoid the consequences of, and consciously decides on a hazardous behavior. The vehicle at that point is potentially a weapon. It's purely a choice that the driver makes, and can reverse at any point. It's a credit to the professional peace officers that more high speed pursuit perps aren't killed.
I also believe that a lot of high speed pursuits are not rationally justified, presenting too great a hazard to the public, peace officers, and the idiots driving the pursued vehicles. I didn't mention felons or suspected felons driving the pursued vehicles, because that's a whole different scenario outside my experience. 11 MPH above the speed limit isn't automatically a deadly hazard to the public, but I have seen it become one with a stupid driver in a very fast car.