“borderline criminal” Are they nuts? What part of kicking a handcuffed man in the chest is NOT criminal? I will give the cops a lot of leeway in how they get the man in the cuffs. However; once he becomes your prisoner, it is your responsibility to protect him.
Remember the Navy SEAL who was Court-Martial for punching a POW? Anyone who has been in the military know you can get a medal for doing your damnedest to kill the bad guys, but the minute he is your prisoner, you have to protect him.
IMO, it is pathetic that a cop can treat a citizen worst than a soldier can treat a enemy.