Not Destroying Someone

The proposition "Not destroying someone certain to kill only postpones" was just presented to me. The passive, defensive wording is, as far as I know, universal among aggressors who must cast their violence as protecting virtue X from mortal peril. I would maintain that "Not destroying someone certain to kill provides an opportunity for them to change", "Not killing prevents unavoidable killing of children and others innocent and a spectrum of of other possibilities to non-destroyed people", which happens in war. The proposition also disregards the fog of war, which is "uncertainty regarding one's own capability, adversary's capability and adversary intent during an engagement, operation or campaign." We might observe that "Not destroying others" is a morally obligatory form of behavior that embodies courage. In all but the most unlikely circumstances violence appears to remain morally unjustifiable.

People who ascribe to the idea that violent destruction is often justified are more likely to deem violence acceptable, feel greater certainty about such judgments, and are rightfully considered more likely to commit or support violence.

The proposition is also weak in describing realistic conditions because it assumes we have the resources and willingness to incur the costs necessary to predict others' decisions and actions with near perfect certainty. Given that merely good decisions are so much cheaper and do not risk commission of destructive, irrevocable mistakes.

People who honestly adhere to this belief are certain to make errors destroying the wrong people simply because humans make mistake. Shall followers of the proposition be killed to protect the innocent victims? The proposition is an unstable concept because of this internal contradiction in violation of Karl Popper rules for logical stability.

Lacking the fog of war acknowledgement is significant in a description of dealing with potential violence. Another major weakness is in its prescriptive actions based on a "false dilemma" fallacy. The proposition assumes the only options for future states are either "wannabe killer A is destroyed" or "victim B is killed". Merely restraining A from killing B so both can lead happy, productive lives is excluded as impossible. We may ask: If we know an employee in military or weapons industries whose choice of work is certain to kill, when might we consider it proper for us to "destroy" the employee to "avoid postponing" violence?

I'm not aware of any conditions where I would consider this course of action acceptable, but I'd be interested to receive scenarios by advocates of the view "Not destroying someone certain to kill only postpones."