First, a review; then, a question.

[NotANeocon]

39. This is NOT intended to be an alibi but to answer the OP ?

It comes down to the LEO training in use of weapons - how to and when you should engage.

From the LEO POV: the man was probably getting a weapon from the lower area of the driver seat, The officer was in fear of his life and had to stop him from picking up the weapon. When pulling was not working he started to shoot. A wounded perp can be extremely dangerous so you must insure your target is totally incapable of any retaliation - and that means keep shooting until the target is incapacitated. At that point your duty as a first-responder is to make sure the person is not armed and render first aid to the injured.

You had 1 second to figure that response out and if you got it wrong you are not going home tonight to your family.

Perhaps if they were trained as Peace Officers instead of Law Enforcement Officers the approach and outcome might be different.