On the contrary. It's a mistake to portray Hitler as non-human. Our natural reaction to Hitler and others as depraved is to disown them as "monsters," and "inhuman," but human is exactly what Hitler was, nothing more or less. It does not aid our learning or practiced skill at avoiding evil choices or behaviors when we dismiss Hitler as "non-human," and thereby excuse ourselves from self-examination. Of course, our purpose is not to excuse ourselves in such a way when we shun such people. We really mean to set ourselves and our culture and habits apart from such people, to say they are not kin, that they are outside our tribe and taboo. That, in itself, is a good thing, but we often carry such language too far, I think, and risk forgetting the very human capacity for both good and evil.
We know both, all too well, as an essential part of being human.
When a cat captures and teases a mouse to the point of exhaustion and death we might be horrified but we generally understand that the cat is doing his "natural born thing," as a creature born free from the responsibilities that come (whether one likes it or not) with "knowing good and evil."
When Cousin Lenny captures and teases a mouse to death we call the men in white coats, because Lenny is human and, as such, is born responsible, whether Lenny has "impulse control" or not and regardless of his education. Lenny is stained with true moral guilt regardless of any capacity for guilty feelings.
Ironically, Hitler and the Nazis arose out of a fashionable flight from moral responsibility, which makes dismissing him as "non-human" particularly dangerous.
Your greater point, that the author is treading dangerous ground by seeming to counter Hitler's "history" with the idea of a man being "quite happy camping it up in the woods" is a correct response, however. Among other things Hitler probably lacked any true capacity for happiness, and hated all who were not similarly messed up. That was a choice for evil that arises all to often from the depths of human hearts.
Great post. I wanted to say something like that as soon as I read the what you responded to, but I couldn’t come even vaguely close to how coherently you expressed your ideas. Just so! Thanks for sharing your thoughts.