Did you actually read the article? That's not what it says. It suggests he became paralyzed by a neurotoxin, an event which no one could have foreseen at the time. Having a map wouldn't have cured his paralysis. I'm not even convinced he was lost.
Yes, had he not eaten the seeds, he (possibly) would still be alive... but he still would have been an idiot.
Only if you stretch the term "unprepared" beyond what people understand the Park Ranger to mean.
Maybe "less than optimally prepared" for the scope of what he was trying to do, but "unprepared" is not fair. "Unprepared" basically puts him in the same category as people who die from hypothermia because they wear cotton clothes.
Personally, I find the details completely beside the point. McCandless sacrificed everything to test his philosophical conjecture and I have nothing but respect for that. I honestly would've thought there'd be more empathy for it here.