Just to play devil's advocate...how many tard brains have you seen...oh, I don't know....sitting at a green light yapping on the phone, and when you yell or honk for them to move not only do they NOT move but they take react with hostility?
Your privilege to drive means don't be a nuisance and waste everybody else's time. Without knowing the words spoken and the details moreso, WTF was the guy blocking the parking lot? Maybe the dentist had a crapload of appointments and he was running late, only to find this butthead blocking the parking lot...then the guy was a **** to him for what HE was doing wrong.
First cause was :the guy was wrongly blocking access to something.
Maybe he DID fly wildly off the handle, but it isn't like the guy snapped and for no reason just started swinging.
Devil's advocate it is.