We've had this conversation before multiple times in the old forums. Awful funny how for as important as details seem to be, that maxim only seems to apply to details conducive to the argument.
Because we also found execution of surrendered troops morally acceptable so as to not endanger supply lines or retask combatants to military policing. We found saturation bombing, incendiary and cluster bombs, morally acceptable, as well as deliberate targeting of civilian populations and residential sectors. We found atomic bombs morally acceptable.
We found mass incarceration of Nazis and suspected Nazis morally acceptable, which you might argue is part and parcel of denazification, justice, and transitioning Germany to a post-war government. Sure, until you consider the Morgenthau plan was the full, forcible, deindustrialization of Germany, and the quiet part of the plan said out loud by its opponents was that meant depopulating Germany by approximately half through human trafficking, forced labor as "reparation", and planned starvation. Yet, under the Marshall plan and in the face of a burgeoning Cold War, we marched many of those same Nazis out of prison camps and right back into the government buildings they staffed before the war.
It's little wonder why that might have been the case. After all, the US didn't jail our Nazis, Nazi sympathizers, and Nazi profiteers at war's end -- we appointed them to the highest positions in the country, and elected them to office up to and including President. We named airports and schools after them.
Seventy years of that shit, yet somehow "Antifa" wasn't really a thing until bad orange man? Fifeen years' of rendition, torture, indefinite detention, extrajudicial killings, militarized policing, and warrantless mass surveillance, the latter half of which many of those now calling themselves "Antifa" defended because we had a black, but more importantly Democratic, President?