This is a nonsense, hypocritical premise. Saddam was, if not our friend, at least considered acceptable, when he was bleeding Irans army in the early 1980s.
Moreover, while we can never know counterfactual history, The ensuing civil wars, rise of ISIS, genocide of Christians and massive flow of migrants out of Iraq and Syria has caused far more death and chaos than Saddam every committed.
Kuwait as it turned out, was “drinking Saddam’s Milkshake” which was part of the reason Saddam invaded in the first place.
We should never get involved in intra-Arab squabbles.