I think the difference is that AI isn't a literal killing machine

Tell that to the Iranian schoolchildren Claude thought were viable military targets (you can't, they're dead as hell), and to the people using AI drones to loiter and auto select targets in Ukraine.

A gun is a killing machine.

A gun is a machine designed to fire a projectile, what you aim it at is what decides if it's a "killing" machine or just a long distance hole puncher.

A bow is much the same, while it "is" a "killing machine," designed for use in war and hunting, the archers shooting at targets at the range near my house aren't murderers, they're just target shooters. Would they use their bow to defend their house, just as I may use my gun that has only shot paper to do the same? Yes, they might, but only one of us is apparently deserving of ire from the uninformed, despite being the exact same situation.

If math wasn't there trial and error would have taken over. (Hell it might have been a lot of that anyway tbh..)