Again, while it is convenient to label them as "irrational" - particularly as we can then use that label to rationalize doing whatever it is we happen to want to do - it is simply not so. Whether their goal is real or attainable or practical or not is all neither here nor there - it is their goal, and it is what motivates them. And they act in a calculated manner, designed to advance that goal.
You did not address directly the question of cultural relativism in foreign policy. There are certain human freedoms that are universal.
Such as the "freedom" to have universal, cradle-to-grave health care, the "freedom" to breathe air that is 100% free of fossil fuel emissions, the "freedom" to advance in society according to the historical victimization of your particular ethnic group. Your argument is wonderful, so long as everyone agrees what those universal freedoms and rights are. Of course, if everyone agreed about what those universals were, we wouldn't be in this kind of mess in the first place.
But, of course, they don't agree, and so it's simply a game of who can impose their universals upon the others. You will notice, I hope, that nowhere do I deny that such a universal morality might exist - what I am telling you is that it is irrelevant. The truth doesn't matter in politics, whether local, national, or international - what matters is what people believe. And most people simply don't believe in your conception of universal human rights, so you have little choice but to simply impose it upon them - "we know what's better for you than you do".
But, the cry goes out, we have the forces of truth and justice on our side! Wonderful. The communists say exactly the same thing. The Islamists say exactly the same thing. I don't claim for a minute that all cultures are equally valid and moral, but in this argument, there is no difference. Everybody says that they have the right to impose upon another, everybody says that they have the right to violate some rights in pursuit of others - what makes you different from them? Why is your cause just, and theirs not? Because your ends justify those means? What happens when they make exactly the same claim?
One could argue that there's an objective test for all of this. The society with the best values is (we hope) the one with the greatest ability to develop the best weapons, the best army, navy, air force, etc. Present circumstances would indicate that the US has won this objective test, thus we have earned the right to preserve our values against all competitors. History has, up to now, been very convenient for my argument. If we had been defeated in WWII, I wouldn't be making this argument. On the other hand, one can point to past societies that had good values (by our standards) yet which didn't do too well. Athens is a good example. The Roman republic is another. Not bad, while they lasted. I suppose the same is true of us. We should make the most of it. In the days of Confucius they called it the "mandate of heaven." Use it or loose it.