First off, I couldn't care less about what the "Race Hustlers" want to do to anything. I'm talking about how this pertains to the central libertarian principle of non-aggression.
The only facts we have are that Zimmerman saw someone who in his mind looked suspicious. He called 9/11 while following him, but the conversation ended. A confrontation ensued, resulting in Zimmerman shooting Martin after a fist fight.
What you aren't understanding is that Zimmerman created the situation by following him and confronting him period, regardless of who initiated the actual physical conflict. Martin had every right to be where he was, doing what he was doing. Zimmerman had no right to confront him in any way. Him being some random stranger, if he was following me I would most certainly view it as an act of aggression and be prepared to defend myself, with violence if necessary.
In our society we have agreed that we will allow officers of the law to detain or question those who are under reasonable suspicion to have committed a crime(I don't want to get into a discussion about the merit of this, but this is the way it is). Anyone else who wants to stop me and ask me who I am, what I'm doing, where I'm going, etc can fuck off, provided I'm not on their private property.