You're arguing morality with your emotions (like a hormonal woman or high school stoner hippie). What he did was stupid, however Martin was just as stupid. Had he chose to just ignore or talk to the fat mexican like a normal person, he'd still be alive. They are both morons and one of them is dead. However, that doesn't automatically mean the fat mexican is guilty of murder.
How do you know this? No one really knows how it went down apart from Zimmerman, that is the entire problem with the case. Trayvon may have tried to ignore him and Zimmerman may have grabbed for him or Trayvon may have went for him first. Only Zimmerman actually knows.
I'm just glad I don't live in a country where an armed man can decide to follow a random unarmed teenager around at night, end up shooting him dead whilst receiving no more than superficial injuries himself, and then actually have a very good chance of walking away from the event scott free
