No, he's not saying Martin committed a crime. He's saying any reasonable person would have feared for their life in this circumstance, and sometimes those are horrible misunderstandings.
It could very well be here that no one committed a crime - that Martin was innocent but acting in a way that a reasonable person would find them very suspicious, and then through a series of misunderstandings he assaulted Zimmerman and at that point Zimmerman reasonably feared for his life and shot and killed him. Just as through a series of misunderstandings, Martin also feared for his safety.
A horrible series of misunderstandings, that reasonable people would agree were confusing, no crime scene, sadly one young man is dead.