Don't think too much about your commute to home from work, most likely you will never see him again. And he probably doesn't want to be seen knowing the fact that you know he flashed his gun on you and doesn't want you to show his license plate.
I get mad too at people while driving but I guess I have to just let it go sometimes.
Had a confrontation with a guy in Eagle Talon in a parking lot, he wanted me to come out of his car and I wanted him to come out of his car, lol, but neither of us did... who needs a black eye. Later I saw him working in Pep boys, and he realized I was the same guy he had confrontation with, fearing his job, he acted so nice to me “can I help you with something Sir” lol... We both recognized each other but neither one of us acknowledged anything about previous encounter. Not worth escalating things.
Just stick your fingers in your ears and say OOHHHMMM few times, it’ll help. Apparently chanting ohm helps relax your brain.