i don't think you can get in trouble for calling the cops for someone, so they get some help, then leaving. i think your allowed to drive by an accident and call the police for them and never stop, and never get in trouble for the accident. if you did get in trouble for trying to help someone like that, then noone is ever going to call help for anyone ever.
all he has to do is deny that he was racing him, that his friend took off fast, then he was flipped over when he got to him and called the police. his friend WAS drunk, so he obviously didn't know what was going on. he might have THOUGHT that i was racing him, but he was racing himself to the grave.
actually if you DON'T call the police for someone to get help when you see them in trouble, in some states, is ILLEGAL.
but the fact is that HE was driving fast and HE flipped the car. HE had a choice, drive fast and risk it, or not. that's just that simple. he basically is getting his friend in trouble to pass the blame, which is just plain evil and straight up betrayal.