The traffic stop would not have happened if the cop even had a clue what the law is, clearly the car had a dealer plate which made the iexpired inspection a non event. He never should have been stopped. The cop should be on leave for not knowing his job, then fired for beating the crap out of an old man that initally did nothing wrong. The old guys only mistske was getting out of the car and walking away.
So did you miss the part where he refused to cooperate and then resist? Act like an idiot and this is what happens. He even said he wasn't going to take it when talking to the other cop.