Joe,
After reading through the Florida Statutes (Title XLVI, Chapter 790 - Weapons and Firearms) http://www.leg.state.fl.us/Statutes/index.cfm I cannot find any reference to it being a criminal act to carry a concealed weapon while on a neighborhood watch assignment. Can you point me in the right direction?
It's entirely possible, however, that the Neighborhood Watch program prohibits an individual from carrying a concealed weapon on watch, but they didn't include anything about it in their handbook http://www.sanfordfl.gov/investigation/docs/NWProgramHandbook.pdf . In any event, if the organization prohibits it (or 'recommends against it') that doesn't make it a crime.
As for Neighborhood Watch consisting of people looking out their windows and calling police, I think you are wrong. While a fair number of folks may do that, I know a lot of neighborhoods where folks walk their dogs, their children, etc., all the while keeping an eye out for anything out of the ordinary.
Admittedly, when George got out of his car, he was likely on his way to violating the Neighborhood Watch guidelines of not getting into a physical confrontation. But that is not a crime, either. A violation of a policy is not a crime.

What is the point of rules that are not enforced?