Looking [1], it does appear that Renee attempted to run the car right into the ICE officer, the wheels were still pointing slightly left, and the officer was still in front of the car. Also in [2] you can see that she was looking directly at the officer during this initial acceleration attempt. The only thing that saved the officer in that initial attempt was the loss of traction due to the icy road.
After that, indeed the wheels were pointing away from the officer and arguably there was no more danger to him, but after the clear attempt to hit him, you cannot realistically expect the officer, in a split second, to re-evaluate if her intentions to hurt anybody changed or not. At this point his life was already threatened. He doesn’t know what she is doing and waiting to find out could mean that he is dead.
The more condemnatory are the 2nd and 3rd shot from the side window. This is pure cruelty and disregard of human life which in a parallel universe could be one of your family member. Anyone justifying this deserves no sympathy from rest of the human populace.
A trained LEO in a self-defense situation is expected to fire multiple shots. Even civilians learn how this works in sufficiently advanced firearms training. See for example https://en.wikipedia.org/wiki/Mozambique_drill . A failure to follow procedure here would be more consistent with "not actually self defense".