How did he expect to justify, legally or morally, a threat to himself or others from people driving away?
I’d also be wondering about temperamentally. I wouldn’t be surprised to find an insanity defense attempted here. Good boy, a real Scout supposedly, then this inexplicable act.
In a more chivalrous environment, a man like this might begin to notice himself being unable to control himself and might voluntarily leave the force, instead of finding it something hospitable to hide behind.
Cops justify that all the time and get away with it. One guy got away with the “fear of my life” excuse in an incident where he purposely jumped on the hood of a car and dropped a dozen rounds into the (unarmed) driver (who had committed no crime).