The difference is that, in the American system, the political faction that engineered that invasion has lost most of its power through a democratic mechanism. The Bush-era neoconservatives are not the dominant force in the Republican Party anymore. Trumpism is clearly opposed to foreign interventions.
In the Chinese system, a similar reckoning about Tiananmen and other atrocities remains unthinkable. The one true Party must be on the correct path, and faith in that can’t be shaken.
As broken as American democracy is, a two-party system fueled by private money is still much better than a single-party system that also controls the money.
In other words, I was answering to what I was understanding as: "Oh it's okay we invaded Irak, because China had Tiananmen".