On the face of it, if you are threatened enough to pull a loaded gun for self protection, why do you not call the police to protect yourself and justify the pointed weapon. (Brandishing)
Regardless of the person approaching his car, no evidence of an impending threat was presented by the gun wielding driver. I believe he knew he was driving like an ass, and the gun was for intimidation. I believe he fled because he knew he had no legal grounds for the gun and panic moved him.
Of course, I could be wrong.
"Peace is that brief, glorious moment in history when everybody stands around reloading". Anonymous
Earp: Not everyone who knows you hates you.
DOC: I know it ain't always easy bein' my friend....but I'll BE THERE when you need me.