Why? What's unusual about considering applying a permanent, definite solution to a problem that one wants to both eliminate and disincentivize?

I suppose I'll venture a guess: considering ending a life as a solution to a problem places a certain measurable value on the life and compares it to the value of solving the problem. Perhaps you find other peoples' valuations strange. For my part, I think that there are a few things that are valuable including people's ability to generally live their lives, but also the ability to live in a society that isn't likely to kill you on a whim. But, imo, it's pretty easy to weigh the cost of things that are threats to those very things, e.g. a murderer.