I don't think he's black and that's the important aspect, not what GZ was but what Treyvon was. Black, Treyvon committed the fatal error of walking around while black in a place seemingly terrorized by this self appointed neighborhood watch vigilante. GZ saw BLACK and called 911. GZ's race is not important here except that the police treated him better than they likely would have if he was black too. They believed his unsupported story because it was only a black boy lying dead. Apparently this town has a history of racial problems and it's fairly easy to see why. So, whatever GZ was it's only really important what he wasn't, Black.
Oh, for the record Hispanic is not a race, at least according to the sources I'm aware of including the US Census. Many people of Hispanic ethnicity consider themselves white. Zimmerman is not an Hispanic name that I'm aware of but I believe one of his parents is Peruvian. Again, whatever he is, it ain't black and that was the relevant racial component here.