One thing I don't agree with:

That's all very easy to say, but I don't think the choice is anything like as easy you're asserting. Johnson knows the mountains, and he knows that the settlers are stuck in a high mountain pass with winter coming on and no food. This is DANGEROUS (ever hear of the Donner Party?) Even if he can persuade the army to take the longer route, the delay means there's a good chance that some of the stranded party will die of cold and hunger before they can be reached. It's all well and good to say "well I don't owe you anything, you're on your own," but you have to live with yourself after. Refusing to help would have meant letting people die. Would you find it so easy to say that, knowing that people will die that you could have helped?

And he also knew that the soldiers were determined to go on anyway. If that happened, there's a good chance he'd still draw the Crow's wrath anyway, since they'd know he led he soldiers off in the first place -- they might not have cared or even realized that he parted with them before entering the burial ground. And he also knows that letting the soldiers go on their own will, again, almost certainly result in deaths. The rescue party will probably not be able to find the settlers in time, and may even become lost itself.

He obviously knew the Crow would be offended by the violation of their burial ground, but he probably didn't realize just how offended. He doubtless hoped they'd be reasonable, that he could make them understand the desperate need, and he'd somehow be able to make amends. And he led the soldiers through because he felt he had a moral obligation to assist in bringing aid to people who would certainly die without rescue. You do understand what a moral obligation is, don't you?

But, it's a pass through the mountains, in fact, the only pass for a great distance, which is the reason Johnson has to take the party through it. The Crows would have known that, so if they wanted to set up a sacred place, why put it there when they could more easily put it in a much less accessible and less travelled location? Of course, what we are really puzzling over here is simply a plot device - without it, the Crows have no motive for killing Johnson's family. But, that's the inherent silliness of it; why not just have a drunken or reckless war party kill his kin for no particular reason other than he is away when they stop by? On the other hand, perhaps Milius wanted to provide a rationale for the murders that would, from his perspective, make the Crows' action justifiable on religious grounds....geez.