Should the world have let Saddam initiate an Iraq-Iran War II? Was he bluffing? We don't know -he's dead. Maybe countries, like siblings, need to duke it out sometimes.
Many years ago there were people calling for Bush (and maybe Obama) to be arrested by the ICC. Bush and Obama are rehabilitated and now there is a more immediate foe who is now to be arrested and rendered to the ICC. Still, we could benefit from examining and have a congressional inquiry into the matter with consequences so that future presidents think twice before committing to war so easily. Then again, the Congress has abrogated its responsibility to declare war, and allows presidents lots of latitude to engage the military in "not war near wars" which are wars in all but name. If they really meant it, they would take that responsibility back.
It's more about degrees of good vs degrees of bad. There is no clear-cut good guy and we have to live with that. There are people who are bothered by the duality.