Nah, this isn't a racist film, and it doesn't condone genocide or manifest destiny. This chapter is told from the perspective of people in a wagon train, and people in wagon trains were frequently attacked by Natives and had to fight them off. That's a fairly minor aspect of the story, which is primarily about the dichotomy between big city folks and frontier people, and about how very different people can become unexpectedly bound together by conversation and circumstance, and also about how trying to take care of weaker creatures leaves us open to danger, and other things too. It's a deep chapter in an even deeper movie, not merely an exercise in technical excellence.