I guess it had nothing to do with the overzealous, wannabe cop that followed him after he was instructed not to, got out of his vehicle to "check the street sign", community watch vigilante.
Sure, there is plenty of blame, but I can't see Zimmerman as having no liability in this. If Martin had been carrying too, Zimmerman may have been the one dead and according to Florida law, Martin would have been in the right.