Unless Zimmerman was carrying it in a hip holster, it's unlikely the yute knew he had a gun.
If somebody, for reasons that are completely unknown to me, came up to me and started hassling as for my reasons for being, I am going to assume possible danger to my well-being. I think most rational people would assume it to be a distinct possibility.
I’m not inclined to stand around and have a rational conversation with a person who isn’t acting rational.