This is true, but we also would readily accept that the Nazi regime bore some substantial degree of responsibility for that massacre, just as it in our reality bore and continues to bear a substantial responsibility for the expulsion of the German communities of Eastern Europe. Those expulsions were appalling and unjust-- if not for Allied hypocrisy, they would have easily been recognized as acts of genocide-- but that's kind of what happens when you behave monstrously toward people.