That's one side of the story, but has by no means been proven.
who had a background of minor brushes with authority and certain details which indicate serious crimes. That may have some limited relevance to a determination of who started the fight, but is otherwise irrelevant to whether or not Zimmerman is guilty of a crime.
I have no idea what world you live on but yes we know that Zimmerman was taking a beating and yes we know the beater was a young strong athlete in his prime. Provable without a doubt in the world? Well no but that almost never happens.
Of course the kids history could have a bearing. If he was an eagle scout with no disciplinary problems, was class president, with a perfect attendance record vs. A kid suspended from school numerous times, with a gangsta persona, numerous brushes with the law. Caught with jewelry and marijuana in his bad, yep the type much more likely to jump on a guy and start beating him.
Whether it would be allowed in court I don’t know but it sure as hell tells you a lot about the kid.