In training sessions I tell people all the time to always call 911. Then, you have on record that you tried. If he had called 911 and reported the accident and then said the OP (Opposing Party) was fine…. and the OP told him it was OK to drive away, he’s more protected.
For any road incident (road rage, accident, etc.), if you don’t call 911, then the OP can call 911 and lie about what happened and there is nothing on record with your side of the facts. You’re toast! I did my self-defense training in October to an outside group. One guy talked to me last week to report that before the election he was hanging political signs and a passing motorist went ballistic. Our guy called 911 and while talking to the operator, got into a situation with the passing motorist. The OP tore the political sign down, knocked our guy down with the sign, was yelling and screaming, and then finally left. Our guy described himself to the 911 operator so when the police got there they knew (or were informed) that he was the victim, not the perpetrator. The police later arrested the perpetrator. Their key piece of evidence was the 911 recording made by our guy. Our guy was completely exonerated.
Call 911. Don’t just leave. Even if the other driver leaves, you stand there on the side of the road and call 911 and report it and explain that nobody is there, but you waited. Again, if the other driver leaves, calls 911, and lies, then law enforcement at least has two recordings to work from to figure out what happened. It’s like having a court hearing with you choosing to not present your side of the facts, if you don’t call 911.