Leslie Felperin says in the article quoted below, "[The] pic lacks the rich, human drama that distinguished "Atanarjuat," prehoned and culled as it was from Inuit folklore. By contrast, Rasmussen feels more like a conventional anthropological pic with a docudrama veneer."I am not saying that you couldn't make an argument for this being a biopic, especially given the title, but Rasmussen disappears quickly from the film. Usually, we watch biopic protagonists become the heroic figure in the film and this doesn't happen here.
Film Reviews: Toronto: "The Journals of Knud Rasmussen"
Variety 404:8 (9 October 2006-15 October 2006), p. 73
Even the fact that Rasmussen is of mixed heritage, and so the stories he chronicles are the stories of his own people, wouldn't be enough, I think, to make this a biopic.
The term observational realism is something that happens between the viewer and what is happening on screen. So I don't think this term would apply in this context.