If there's a trial, the jurors will decide the answer to that question. As I posted last night, Dershowitz thinks the charging document is so legally insufficient that there's a good chance a judge will throw the whole thing out. Admittedly that would take a brave judge. And Dershowitz is an opinion machine. But he is a lawyer, and a very prominent one at that, who has won some very big cases along the way (right, Claus?), so maybe we ought to give his opinion some credit.
Was this community watch organization in compliance with whatever rules apply in Florida? Was it recognized by the management of the complex? Zimmerman was licensed to carry that gun, which means he had to jump through some hoops to get the license. Possibly some training on its use. I was in a Fry's grocery store a week ago and a guy dressed like Paul Brinigar in "Rawhide" was fondling the vegetables, wearing a belt with a holstered six shooter on one hip and a Bowie knife on the other. Nobody was paying him a bit of attention (except possibly me).
I've posted before about this magical belief gun types have that "if only somebody had been armed it would have turned out differently." What they NEVER consider is the "difference" they're talking about could mean a higher body count of innocents. Sure, if some kid at Virginia Tech had been armed, maybe he could have gotten Woo Tang Klan between the antlers. But your average college kid, in an extraorinarily tense, target rich environment is just as likely to miss or hit someone else, IMO. Am I supposed to feel a constitutional glow because some ATO pledge hit my daughter in the face?