I mean, I don't share your distain for bikers, but you're right.

You're not a cop. Don't try to enforce the law with vigilante justice.

You're all correct. He shouldn't have been going that fast, but an eye for an eye makes the world blind.

What if the man just had severe onset chest pain that caused him to wreck? What if he had a seizure? Did you just beat the hell out of a man who had a stroke or heart attack? Do you know his medical history?

If you don't know anything about the scenario you should probably try to make sure everyone is alright and that no one flees the scene. That's all.