Can you please describe whether Ruess’ story helps to bolster Krakauer’s argument that Chris was not crazy.

I think the story helps deffend Chris's idealism and sense of adventure. John Waterman was actually mentally insane, but Everett Ruess was, like McCandless, simply deeply in love with the land, very romantic, and passionate about living by his principles. These comparisons show that removing oneself from society and living riskily can be a symptom of insanity or stupidity, but it is not inherently so.