That is not a definition of "morality". That is the Law of Armed Conflict's Guidance With Regards to Collateral Damage Produced by Military Operations.
No it's not. In fact, that exact guidance was given, though too late. Nor did I ask retroactively about 9/11, I asked IF THAT HAPPENS AGAIN, what is the "moral" decision. Tell us Boo - which is more moral - to kill 400 through action? Or to kill 4,000 through inaction?
I have been involved in similar situations, where the decision is made to take action that will probably kill non-combatants in order to save many more non-combatants. When a guy driving a car-bomb puts some civilians inside, and drives that VBIED at a crowd; you don't have time to beg him pretty-please to step out of the car so that you can get off a single, well-aimed, "surgical" shot. Instead you light up the car, and kill all those inside, but save the crowd. 3 non-combatants dead, 20-30 ish non-combatants saved. Then you clean up the pieces of the kids inside and you throw up and you hate yourself and you hate the enemy more, and you drink as much alcohol as you can pour down your throat once you get back to the states. You think this **** doesn't happen? You think that it doesn't happen all the ****ing time? Who the hell do you think we are fighting - Mary ****ing Poppins? What a pretty ****ing world you must live in. No, we are fighting rat evil bastards and assholes who don't think twice about throwing up non-combatants as human shields if they think it will increase their odds of operational success or organizational long term survival. Thank goodness as left wing and hairbrained as he is, even Obama isn't that much of an idiot - which is precisely why he kept the anti-terror infrastructure in place after campaigning against much of it.
But let's be clear: is it your argument that reality does not present US forces or decision makers with situations where no matter what they choose, non-combatants will die?