I will say that I do not approve what this man did but I can understand how someone would get sick and tired of the lawlessness in California.
What the man did is plain wrong and evil. You don't shoot at a passing car just because you don't like the noise.
A couple decades ago my car club was having an annual meet at Mt. Shasta in Northern California. While driving through a neighborhood in Shasta City in a group of 30 or so vintage sports cars, a man came out of his house and blocked the lead car while holding a metal baseball bat and threatened us. He didn't like the noise (happened during the day in the afternoon) and was very hostile. We managed to calm him down and promised to stay away from his area. Imagine how different it would have been if he shot one of us (well, a couple dozen of us would have beat him up, a few of our guys were cops and firemen).
Usually we would go on spirited drives on mountain roads or highways, but our lead guy took us through a neighborhood (a mistake for sure).