It was a needless wrongful death that were the direct result of his actions, I don't know that seems pretty manslaughterierish to me. Yes I get to make up my own words.
I don't have a problem with guns, or carrying one. This isn't an issue for me. BUT you have a responsibility to act responsibly with one. I think having one made him a little brave and when things didn't play out like he thought they would he found out he wasn't very brave and he panicked. I don't believe his life was in danger, I don't believe he really thought his life was on danger but he panicked and he used his gun when he shouldn't have. If he hadn't gone for his gun, and defended himself with his his own hands and fists, he still would have walked away, both of them would have. If you kill somebody because you are behaving irresponsibly, yeah you should be punished. He shouldn't get to walk away with a "oh you Zimmerman, that was just silly. Don't do that again."