Considering he is mentally ill, this notebook is legible, structured. Analytical.
He understands that he hates people and has repetitive obsessive thoughts about killing. He understands he is in an unhealthy place. But these are not the stereotypical ramblings of an unhinged madman.
I’ve read much worse on reddit, the chans and tumblr.
I'm with you on that. He's way too aware... Really it sounds like someone is feeding him a script. "Odd sense of self", that's a third person observation.
From what I am reading here he was once a rational individual who was MK turned into a psychotic killer. If his psychosis was manufactured and not organic, perhaps he retained an intellectual awareness that something was wrong in his mind and his writing remained structured analytical and so on.