@snood,
I'll say it again, worst possible case, the kid could have just decked Zimmerman and walked away, and nobody would have died. What actually happened was that the kid sucker punched Zimmerman, and then pounced on him and was in the process of literally beating him to death when he got shot for his efforts.
Trying to kill somebody with more firepower than you have has ALWAYS been problematical and dangerous. Cursing George Zimmerman for using a gun is like cursing the Masai for using their spears on a rogue lion or like cursing our own ancestors for using atlatls and javelins on Neanderthals intent on killing and eating them. Wake up.