If this story is supposed to be an allegory on the Iraq war, then the flaws in it are numerous.
(1) The US did not actually witness Saddam committing crimes that would justify intervention; most, if not all accounts, were from Ahmed Chalabi an the Iraqi National Congress, as well as similar partisan sources.
(2) The UN found that there was not sufficient grounds to invade Iraq based in part upon premise #1.
(3) The stories about Saddam personally murdering children were war propaganda, nothing more.
(4) Saddam was no threat to his neighbors; he could barely defend his own country, let alone attack another. Consequently:
(5) Saddam was no threat to the United States.
But it doesn't end there. To continue with the scenario presented in the first post...
Say that the hypothetical situation takes place. Instead of taking a small force up to the murderer's house, you launch an all-out assault on the neighborhood. You bomb homes, shopping centers, hospitals, & whatever you deem necessary to put the population of the neighborhood in "shock and awe." You may murder as many people as the murderer did, but that's okay because it's just "collateral damage."
After you capture the murderer, you hold him incommunicado without charges or trial by jury. After the families of those he murdered demand you release him into their custody so they can give him a fair trial with the entire neighborhood involved, you refuse, because you always know best, and they're just a bunch of uncivilized ingrates.
But it doesn't stop there. Instead of turning in the murderer to the police and leaving his family and the neighborhood in peace, you instead get a bunch of your friends together and occupy the neighborhood at gunpoint. You routinely invade the homes of, and incarcerate, people even remotely suspected of being in cahoots with the murderer without a fair trial. You then leave the prisons unsupervised, allowing your friends to torture those captured. You restrict the press to only "pro-you" outlets, because anything else might publish something that might even remotely sympathize with the murderer. Even when the majority of the people in the neighborhood wish you to leave them in peace, you stay, because you're automatically right & you always know what's best for them. You are, after all, the most civilized person in the neighborhood, because you're the only one with big-screen TV's, boutique computers, and the ability to dine out at expensive restaurants, not to mention lots and lots of guns & bombs.
I wonder how, after presented with this scenario by his father, the child would react.