If Zimmerman assaulted the kid, then sure.
If not, and the kid initiated the physical fighting, then no.
For the record again, the Castle doctrine doesn't apply in this case, and Zimmerman couldn't have justifiably killed the teen just because he FELT threatened.
I'm going to assume that Florida has the "stand you ground" clause of self defense outside the home. That being said, if the kid didn't have a weapon, it will probably be very difficult for him to claim self defense in court, unless the kid was so much bigger than him, that he could have mauled him with his bare hands.
Even if he is not prosecuted by the police for this, Florida state law may or may not allow the family to sue Zimmerman in civil court. Some states say that if a shooting is declared justified by the police, the shooter is immune to any civil case.
I'm a big fan of concealed carry by civilians, but the way this guy acted is so far out of line with how a responsible carrier should act, at least with the current information.
Agreed, from what I know of the "Castle doctrine" it allows you to stand your ground if attacked. And I believe ( I know in MI) there is still the expectation that a firearm can only be used in response to a reasonable life threat. And while a weapon isn't required, certain extenuating circumstances are. The attacker must present a serious physical threat (being significantly physically larger or far younger like a older teenager attacking a senior citizen). Neither seems to apply in this case.
I don't think Zimmerman comes close to meeting the basic requirements from what I've read so far. But I still get the feeling we're missing something. How old and what size was the "kid"? A 17 year old "kid" who played football and evidently beat up Mr Zimmerman certainly had some anger issues. Why wasn't the kids first impulse to be on his cell phone calling 911 about the guy following him? Why was the kids first response evidently one of confrontation and anger?
Zimmerman obviously crossed the line and inserted himself in a situation that he had no business inserting himself in. This alone IMO makes him guilty of some form of homicide. He started the chain of events that led to the confrontation, no doubt. But, why would any culture be so worried about getting "dissed" that a teenager would physically assault someone for being followed? A tragedy was the result, this we can be sure of.