Except that the officer didn't drive up and shoot him.
He shot him because Tamir raised his jacket and reached in his waist band as the officer exited the cruiser, which to any rational person looks like a weapon drawing motion since most weapons, especially firearms, are kept at the waistband level.
How many times have people been told, when approached by police make no sudden movements and reach for nothing until commanded!
I know if I'm exiting my vehicle and I see someone make a motion like this as I am exiting, and after being given a description of this person holding a weapon and pointing it at people, I'm thinking they're going to draw down on me and possibly try to shoot me.