Okay, first, this kid's 'criminal record' consists of using a cell phone, failing to signal, following too closely, driving the wrong direction, trespassing, and possession of pot. Doesn't sound too different than any other 22 year-old average American male.

Real criminal on our hands here, lol.
He seems like an unexperienced, young, frightened kid, who let panic and fear rule his reaction. I can also see that he may have meant to accelerate slowly, but his body was reacting to the adrenaline that was no doubt pounding through his system and the gas was punched. I have experienced that myself, and ran into a metal pole by accident, (put the car into drive, not reverse and then punched it). I don't think a homicide charge is accurate in this case.
And honestly, if this so called 'victim' had so little control on his temper, as well as being as exceedingly stupid as he appears to have been, something like this was bound to happen, if not something worse. That guy sounds like he was a nut case and I personally feel little sympathy towards his situation. If this wouldn't have proved fatal for this man, he could have been charged with (at the least); harassment, assault, reckless driving (insert numerous traffic citations here), road rage, and damage of private property. Who sounds like a criminal now? However, since he's dead, let's feel sorry for him and forget all the violations to others/the law, shall we?
As for the results, we'll see what happens.