I consider this a rather dubious line of reasoning, culminating in the fantastical assumption in the last line. Depend upon it, none of our allies in any war we have ever fought volunteered to fight "in our interests." Were the French royals fighting in our interests in the Revolutionary War? Were Stalin's soldiers fighting in our interests? Absolutely not. They are motivated by their own distinct set of interests. The fact that there is sufficient overlap in their interests and ours to constitute them allies is a very different matter from having the same interests. This guy is arguing that whenever we go to war we have to accept the responsibility either to fight indefinitely until victory or to be prepared to relocate whole peoples and nations to the U.S. There are cases in which neither option is acceptable or reasonable, either from our perspective or from that of our allies. I might add that if this were adopted explicitly as U.S. policy it could lead to a major increase in isolationist tendencies. It effectively punishes us for trying to create decent regimes in other countries. This is like insisting that a man who saved several children from a fire, at risk to his own life, must now adopt those children since he failed to save their parents. It punishes good intentions and encourages a dangerous isolationism--which is far more pernicious, morally, than the occasional failure of well-intentioned international intervention.
From a moral perspective there is no more reason to relocate Afghan allies to the U.S. than to relocate Congolans caught in the middle of that nation's civil war. Neither group was promised this privilege. Both groups face the prospect of being murdered by their countrymen and may, to that degree, be considered equally innocent and worthy of rescue. And there is no proof that our intervention in Afghanistan caused or will cause an excess of deaths above what would have occurred had we left that land to continue its endless civil wars and theocratic gambits. Perhaps we are more culpable for the millions of deaths in Congo since these might have been greatly reduced had we intervened. Another moralistic perspective might be this: it became clear within the first few years that the Afghan war was unwinnable (since the Taliban are based in Pakistan and Pakistan is neither our ally nor readily conquerable). This means the lives lost and monies squandered in the last 2-4 years were wasted in a futile exercise. And, remember, money at this scale, properly spent, could actually save lives instead of facilitating finishings.
