I don't hold Martin blameless in the situation at all, but this is definitely a case of dysfunctionality in that neighborhood's security plan.
There should have been someone responding to Zimmerman's call for some level of backup. It is not a matter of cowardice, but knowing that if are making contact legitimately, you want witnesses. I don't blame any single player in that, I blame all of them, from the shooter to the parents of the truant teenager to the community that decided not to give a crap until the bullets were flying.
The case has been covered in just about every single issue of "The Final Call", the national Black Muslim publication, but they seem to always ignore and marginalize every single one of the retaliatory attacks that has taken place since that incident and most of those were very deliberate attacks with often very deliberate messages of terror at the street level.