Well, the game works on (at least) two levels, I think. One is that which you explicated above, but I think the other is a more general point about men under stress. The source of the stress can come from many places - for Vietnam, it comes from the sense of failure and utter futility that comes through in much of the literature. I actually have yet to see Apocalypse Now (I know, I fail at good movie watching...), but I imagine it fits the bill. In a more general sense, though, men can turn on each other for many reasons. I think Carry could work for a unit of Russian soldiers in WWII, forced by the political officers to stay at the front even though the fight is futile, for example.
As for a greater political statement - well, I agree that the subject matter is inherentely politically charged, and that Vietnam is an important era to compare and contrast the conflicts of the day with. I think that the game is certainly a vehicle to air and explore different opinions about Vietnam and how it affected those in it. I mean, nothing is stopping you from playing a character convinced that the US is doing the right thing, or even one that defects and "goes native" (though I think you would have to get creative about that one). Am I trying to make a statement? Not particularly. I mean, I agree with your analysis for the most part, but I'm not trying to really change anyones mind here. Thats why I try to be clear that the game is based on the Vietnam "genre", and not historical reality.
Is that a satisfying answer? I'm totally game for more discussion if you have more you want to talk about.
-Nathan