I think that Krakauer's description of McCandless is too forgiving of McCandless faults, and if this is intentional, it's done well. The way that McCandless's life is romanticized until his death is one I didn't understand, even from the beginning of the book and it comes off as a fan-fiction of McCandless life and his inspiration, but I think this plays a role in the story. The way it's written, with barely any time spent describing things that are subjectively wrong with McCandless and instead, by focusing on the idealistic almost fanatic obsession with untouchable beauty and isolation, using this sense of wonder to toy with the reader's emotions throughout the story. The hard comparison between the theatrical description of McCandless's wayward life vs the mysterious and abrupt descriptions of the boy's death jostles even the most skeptical reader's perspective. You are sat in McCandless's shoes, almost horrified with the way this world is idealized and the way the author writes with a pair of glasses tinted past rose and then contrasting this sense of comfort and uncomfortableness with abrupt fact. I think that's where the creative nonfiction get's creative, when the use of mystery and emotion is used to manipulate how the reader is meant to feel and what they're meant to understand about the character of Chris McCandless.
I think the choice to begin each chapter with a picturesque description of the wilderness and small towns or native flowers is an intentional set up. Descriptions like "the travelers through this hard, dry country have for centuries relied on the oasis" (88) or "in late spring [the bear-paw poppy] produces a delicate golden bloom" (25) or "sleepy little cluster[s] of clapboard houses" (15) are meant to dull your senses and submerse you in a feeling of comfort and familiarity, as McCandless would have felt as he traveled the US and embarked to Alaska. Each description of his close friends familiar faces or giddy postcards make you feel connected to the story and to McCandless's perspective in a special way, and when the description quickly becomes blocky and loses it's mystical air when describing his death, you feel as if he has died in the story. Slowly, as the circumstances of his death are revealed, so are the hard truths behind his personality and perspective, and as the story progresses I hope to see this use of emotion and description continue to connect you to the story beyond that of, lets say, Everett Ruess or Carl McCunn.
I think McCandless is naive, overly-idealistic and slightly unstable, but I also empathize with his determination and spirit, and I think the book sets out to harshly contrast those two ideas and make you feel the discomfort that comes from it.