I think the cop was waiting for firefighter/em personnel to show up so he could choke and arrest him.
If he cop did try to help he might have gotten confused if the victim twitched. The cop might have yelled “resisting arrest”and then beat up the victim or shot him.
I do realize that not all cops are bad. But the public image will only get worse unless good cops take incompetence, cover-ups and criminal behavior in the police force seriously, and that means real sanctions and punishment. The rise of SWAT raids, the militarization of police, and acceptance of federal money is NOT a step in the right direction.
Correction, he should be she.