I'm a bit amazed by the armchair QBs on this one. Wow.
Look, some crazy dude starts trying to bust the glass on your car...he is standing and you are sitting, strapped in. If that glass breaks, how are you going to defend yourself? Once he reaches in and grabs you, it's too late to go for the gun.
As for "two adult males, no uneven force", remember that a soccer coach was recently killed by a single punch from a 17-year-old. It's not about fighting fair. The law does not require you to start taking blows before you defend yourself. If you are armed the worst thing you can do is let it close to blows before you try to draw your weapon; it will likely be turned on you.
The OP stopped a threat and everyone left physically unharmed. The police agreed. I'm a bit stymied why people still have a problem with this?
As for the people questioning why he didn't continue backing up because he had seen kids behind him, but he had mirrors etc...several months ago I was driving with my family on a four lane freeway and a guy was driving slow (~7mph under speed limit) in a BMW in the left lane. So I swung in a lane, casually passed him (using blinkers with plenty of space), no big deal. The guy went ape, laid on the gas, and started to come around me on the shoulder (2 wheels on grass at 70mph and accelerating). As soon as I cleared the big rig I was passing, I swung in 2 lanes (as far as I had clearance to go) to get away from the idiot and just let him go. But no, he pursued me, cutting off the semi and nearly jack-knifing it. He deliberately tried to side-swipe me, I tapped the brakes just a bit and held steady, I still don't know how we didn't make contact. Once he was in front of me he locked up the brakes, I got left one lane again so he accelerated and got in front of me to block me again.
By now I had grabbed my phone from the console and held it up in the windshield to make him think I was recording (I did not have time/attention to actually manipulate it to start recording). He saw it and suddenly became a model citizen. I snapped a photo of his plate and called 911, he shot off the next exit and with no video of the incident of course nothing came of it.
Afterward my wife asked me why I'd almost let him hit us, why I had not cut over another lane or braked harder. She indicated I had plenty of room. But in the heat of the moment, focusing on the imminent threat and avoiding the collision, I did not have TIME to check all of my options. I had to act on my mental picture as it existed the last time I had checked my surroundings.
If you think you have a bunch of the kids next to the street right behind you, I would have done no different than the OP.
BTW it's all about avoidance. In the example above I was carrying, and the exit the road rage driver got off was actually my exit. I was on the phone with 911 and could have followed him off (it was my way home) and told them where he went. Instead I took the long way just to get as far away from him as possible.