Unmaned armed drones would reduce the personnel risks and they are very accurate.
That is true, and we already had a drone, or perhaps two in succession, at the scene. That however leads to the maddening non-answer to the question of whether the drone was armed. Except of course that the media doesn’t ask that question, either. Pat Caddell is right...
Another consideration, though, is that while a drone could certainly have taken out that mortar, a drone by itself could not hold off a sustained attack, if the attackers were determined and well armed.
However, as you said, the question is less that of the means, and more that of the decision makers and their mindset.