What if you want to call the mission off? Let's say the enemy gets a few key hostages, and holds them in this building. They'll be killed by their own side.
Revokable weapons are weak; irrevocable weapons are strong. It's the same logic as mutually assured destruction, and evolutionarily similar to blind rage.
FWIW I believe autonomous weapons are inevitable because drones cannot be used against technologically sophisticated enemies that can jam them. The hard requirement for continuous communication is exactly what autonomy is eliminating.
The enemy didn't necessarily break the Geneva convention.
Pulling the trigger far in advance of the resultant action increases the risk of disaster, disaster that could've been averted based on the richer dataset available closer to the scheduled time.
They didn't have to. We're just going to say they did anyway because they are evil bastards (TM) and we can't possibly be anything but the good guys.
This scenario is the exact same scenario as a current ballistic missile launch. There are no safeguards for those systems that could be intercepted and interfere with the use of the weapon.
Send more drones to kill your own drones? If the drones can be fed new instructions in the field, then the enemy can feed them fake instructions to shut down.