You can't be "just a busybody" when you have a gun. There's also no need to maintain visual contact. You call the cops, and that's it.
When you take on the huge responsibility of carrying a gun (which, I do) there are certain things you must know.
And if the cops show little interest in responding to anything that doesn't involve traffic fine revenue? What then?
“You call the cops, and that’s it.”
The cops in our area take an average of @60 minutes to respond. Our neighborhood was victimized by a series of burglaries a few years ago. The neighbors got together and now few strangers come through without being”chatted up “ or their tag being taken down. Guess what? No more burglaries. Nobody’s lookin’ out for us but us—and that’s the sad truth of the matter.
Are you attentive about others in your surroundings? Do you take stock of what other people are doing?
Anyway, my remarks to you go back to your "if Zimmerman actively pursued Martin as reported, does the law still protect him?" I gave an "it depends" answer. Your criteria, that if he has a gun he can;t possibly be a passive observer, is absurd on its face, as your own admitted conduct of carrying a gun shows.
The law protects Zimmerman very well if his actions aim to avoid close contact, confrontation, and use of force; even if he is armed.