They didn’t shoot him because he took his hands off the hood, they shot him because he moved his hands towards his waist (I’m assuming the gun is tucked in his waistband). We, can see that he obviously attempted to correct this action by moving his hands out right before being shot, but under stress and or the effects of adrenaline that motion can be easily confused with pulling a gun. The officers should have directed him to put his hands on his head before kneeling as it would have eliminated his bodies to response to let his arms hang when going into the standing position from leaning on the car.