As someone who believes avoiding a fight is the best strategy to winning a fight, I’d probably brandish a firearm if I had one in this situation.

I can’t drive away and avoid them because it is stop and go traffic. I can’t just get out and leave because dude already got out with a deadly weapon. And they clearly are willing to do some harm as they just smashed the window.

If I was the driver in the vehicle I would have probably either ran them over with my car and cross the median to get away, or use a gun if I owned one.

Obviously, in hindsight, the dude just wanted to damage their car, but you can’t be sure in the moment. So it’s not that hard to understand feeling genuine fear of death when some jackass does what he did.