A normal person would recognize their inaction to a known threat caused the death of innocent bystanders.
MC/Cain? He'll probable bemoan "not letting a mass-murderer, slaver, kingdom-traitor get to live (to be punished)", completely ignoring the victims of their inaction. Or some other moral idiocy. To which their cardboard cutout supporters will call them "kind" for, and attempt to console them.
It takes a special kind of sociopath to think like that. I don't get why JP WN authors are morally bankrupt to that extent. I want to see a protagonist try to pull this stunt, then be slapped by their supporters, and called to the carpet for their naiveté. The families of those that died, because of protagonist's peace-drunk mindset, to wake them to reality.
Even Aesop's Fables have moral lesson to them; Isekai junk food? Not so much. (WOTD: Heiwaboke)