Point #2: Culture and language differences lead to misunderstanding of cultural relevance.
Sorcery is, or more recently was, incorporated into Tarahumara culture. At a broad level, it can be used to explain things that are different and unexpected from their worldview. Going to Leadville and racing hard against a white woman, among a cultural and language barrier, would certainly fulfill that criteria. I have no doubt that most of their usage of the term is based on fear of the unknown, but McDougall and American readers stretched it to a more American view.
Another example: some Tarahumara recently ran the Run Rabbit Run 100 in Steamboat, and both dropped. One due to injury. They both asked much about the course itself and about "bears." Why bears? Someone speculated on irunfar: "The fear may be founded in superstitions that the Tarahumara tribe believes in." Whatever. There are bears roaming around in the area this time of year especially, and some bears got into drop bags at an aid station the previous night. These guys are running all alone (no pacers) through the night in a strange country; on, as it turns out, a confusing and poorly-marked course in which people got lost. The simple explanation then is frustration, uncertainty, and fear -- but a more "romantic" portrayal would involve bruin superstitions instead.