In my country, Kentucky, if someone is threatening your life or serious bodily harm, you are within your legal rights to use deadly force to stop them. Most people interpret that as a right to shoot them, which it does. But running them down in a car is also using deadly force to protect yourself and those within your charge.
I can tell you that if, instead of running him down, he had pulled out his legally carried gun and shot the man dead, that would pretty much end the story, at least in my country.
Wait Kentucky is now a separate country?