In this case, the cop did have reasonable suspicion. A call(s) were made about someone in the area that seemed suspicious. The cop goes up to the guy, asks him what he is doing, and asked for ID. A cop can ask anyone for ID, but depending on the situation, a person can decline. The suspect in this case, over reacted and acted very angry toward the officer. The suspect then put his finger in the cops face. That seems safe enough, but in that range, a fist can be thrown very quickly before even a trained fighter could react.
If you had someone that angry that close to you with their hand in your face and a shovel in the other hand, are you going to assume you are safe? It would be impossible to react to anything at that close of a range, weapon or not.
I would guess that the reason the cop reached out was not to push, but to make the guy put his hands down so the cop did not get hit.
I am all for police accountability, but I dont see anything wrong with what the officer did.