Nice analysis, I would go even a bit further and posit that Bird's wonderful treatment of Hughes' story also directly addresses one of the fundamental questions of Existentialism: "Is this all I am?" The robot is a machine designed for destruction, but as it continues to interact with humans - fortunately, mostly moral, caring, conscientious humans - it comes to discover that one need not be limited to the confines of one's "programming", that one develops true character by confronting moral dilemmas and making active choices in response. In this case, "I am NOT a gun!" represents such a crossroads point, because, truth be told, it IS a gun, a very big, insanely powerful gun. But, making the choice to not BE a gun, to be something different, something better, to BE "Su-per-man", if only for a moment, and even at the supreme sacrifice of one's own life for the greater good, is a significant, evolutionary step forward. It's what makes us human, and what ultimately separates the good guys from the bad guys.
As one of the animators on that movie...it's always good to hear such wonderful things about this movie. At the time...we all knew we had something wonderful and we were excited about the future...but.as always, moron execs got in the way. And the whole crew went their separate ways. But we DID have lightning in a bottle at the time and it was great to work on this fantastic movie with a truly FANTASTIC crew.