So basically, Babs is telling him that she thinks wearing a Bat and using a gun at the same time is shiny, and Batman should just shut up? The gun and the Bat-symbol are in complete opposition.
I mean, can you imagine what Bruce would have said if the murderer used a pencil?
Obviously an object created for the purpose of killing people and an object that was created for something entirely different but that can still be dangerous in the wrong hands is the same thing.