Not true. I can muster a fair amount of compassion for co-ethnics and other men of good will. I'll admit to tapering off in my enthusiasm and compassion for "saving" evil men and enemies.
but the idea that waging war to get rid of Hitler was not a moral imperative
No, your problem is that you see no problem with killing 40 million to prevent (well, not even in the case of Hitler - nobody was trying to prevent anything) someone else from killing 10 million.
Lets say you have five children. Would you kill four of them trying to save the life of the fifth, or is it better to just let the fifth die and the other four live?
It'd be an easy choice for me if they were my children, much as I'd hate to lose one, I'd hate even more to lose them all.
Anyway, back to Hitler. If there was a moral imperative to wage war on Hitler, where was your moral imperative when it came to Lenin and Stalin, or Mao? Is the moral imperative only operative when Jews are getting killed? That seems to be your position here.
By rights, if there is a moral imperative to put an end to genocide, Hitler had a moral imperative to invade Soviet Russia and smash the Communist death system. Maybe we should have helped him ... its your logic at work ...