In that it wasn't as such... but it was also totally understandable.
To use a German example: I don't think anyone would argue that the firebombing of Dresden was moral. It was effective... but that's not the same thing.
Of course... this is war we are talking about. So, morality is already about shades of grey.
If you wage war on foreign nations, and allow your government to do so, then you shouldn't be so surprised when it comes back to roost. No, the WTC attacks were not justified. But they were definitely to be expected, given the carnage around the world that the USA has been propagating now, for 80 years. When your nation maintains its moral authority to indiscriminately wage war around the world, you should not be surprised when that war comes to your footstep.
How can you even say that when you are replying to a comment talking about totalitarian regimes like nazi germany? This is one of those horrible "im more cartoonishly pessimistic ergo realistic than you" internet ideas.
Can you really maintain such ignorance in the face of the political reality, that governments gain no powers from the ether but rather - directly - from the support of their civilian populations? Are you stupid, or just young and haven't gotten to that part in civics lessons yet?
Whats unsubstantive about their point of view that the people are responsible for their governments?
This is a widely accepted truth, throughout history and international law - so while I do agree that the poster you're warning is a bit rude, I don't agree that their position is unsubstantive, one bit. I can understand their exasperation at the many claims that "governments can just get away with whatever they want to do because the people are powerless anyway."
There are many in the HN crowd who would like to see civilisation improve itself for the better - failing to take responsibility for ones government and its crimes against humanity is not going to produce that result. I would urge you to reduce your comment to pointing out the posters' rudeness - and remove your tacit censorship of their, very valid, point.
Perhaps in your weathered age you've heard of and maybe even read the Declaration of Independence (in the case of the USA)?
"According to the Declaration of Independence, the government gets its power to govern from the people that it governs. As the Declaration says, Governments are instituted among Men, deriving their just powers from the consent of the governed."