We can choose not to build nuclear weapons: they're weapons with lots of weapons specific research associated.
But drones aren't. The technology is general use: it's a natural consequence of a couple hundred incremental improvements, and the only difference between "weapon" and harmless is a software parameter and a payload.
"Find and kill this person" is indistinguishable to a search and rescue AI, just with "on found and centre camera" triggering a bullet or a spike or a bomb and not text notification.