Killing is abnormal. Whenever someone is intentionally killed, it is a failure of society and an incredible tragedy.
For the victim of killing, there's no difference between "being killed" and "dying". It's not that your life gets less valuable or your pain gets eased if you die from natural causes. And eventually we all die, death itself is not abnormal, then what's the big deal about killing?
Killing is not a tragedy. Dying early if you could live longer is a tragedy.
Taking someone like that out with a bullet or a drone is much less risky operationally. They also avoid the additional geopolitical complexity of needing occupying forces in the relevant country.
Maybe there should be some pre-operation due process rights, but it seems callous in other ways to insist on non-violence in all cases. Especially in response to catastrophic violence.
A couple of centuries ago violence, wars and killing were a way bigger part of human lives, and it has been like that throughout the whole history.
I don't like glorifying violence, but I want to acknowledge that it's a natural part of life. Some can afford not to deal with it, some cannot.
It ist only the distance you mention that even allows you to glorify the ultimate dehumanizing act.
That it is even romantice in the context of child soldiers speaks volumes.