Being the Devil's advocate here. Nothing here in this story tell us of his demanor toward the prosecutor. I have been to enough court cases in my life to know that if a person is humble and contrite for what they did it often times will work in their favor when it comes down to working out a plea.
There's nothing to indicate it in the story, but what if this guy approached the prosecutor with this same cockiness that they said he was known for as an athlete?
Once again, drawing from my experience, when a defendant approaches the prosecutor with an air of cockiness and arrogance, more often than not that prosecutor is going to go after them like a pit bull, archaic law or not.