Yes, NUNS is a victim and has a right to defend itself, even if the bugs were provoked.
Not sure why you're quoting something from RL, as my quote was simply from Ender's mentor who told him to stop feeling sorry for the enemy simply because they weren't the monsters humans thought they were. The Buggers slaughtered humans because they didn't realize they were sentient, but that doesn't excuse their massacres.
Morality in war isn't absurd at all. If it were, why don't first world nations let soldiers rape, cannibalize and slaughter captives at will? And punishments if those rules are violated?
Fighting is a part of human nature, but there can be honor and humanity in it. Since we're using real examples I'll point out the Desert Campaign between the British and Rommel in WWII, noted for being remarkably humane.