The cops barely nudged the guy when he idiotically ran up on them, but he was such a clutz he stumbled back like a flailing clown and inexplicably made zero effort to keep his head up.
Barely nudged the guy is right.
The old guy was backing up and tripped is the way I see it
>> The cops barely nudged the guy
Notice the agitator has big stride while approaching the cops, then when pushed back, he also takes two large strides, but after looking to the ground, he allows himself to fall by shortening his backstep.
Also, the cop from behind could only see the agitator’s hand moving towards the officers gun.