I probably would have handled the situation exactly as you did when I was younger,
(which is not to say it was the only way to go...)
And, you achieved the desired effect.
On the other hand, people who are deliberately provocative narcissists (you know, azzhats,) are generally that way through and through. He could indeed report the incident to the authorities and even file a charge that the owner of the vehicle verbally assaulted him, and as noted above even if the cops knew he was the cause of the situation, they would be obliged to follow up on his complaint.
One of the real issues with packing heat is that you have to go so far out of your way to avoid any situations where it can be used against you. You actually have to take more guff and back down faster with a gun on than when you're not carrying, to avoid the perception that you provoked a situation so as to be able to pull the gun.
Next time, go find the manager and file a complaint. (And then follow the guy to his car and take a photo of his license plate!!)
Just sayin'.....