I'm gonna go out on a limb here and speculate that he has probably never read Mein Kampf--and compiled his list of favorite books by thinking of what would be most shocking to a reader.
Am still unconvinced that his motive in the shooting was political. He may have just wanted to shoot someone famous in order to call attention to himself.
Have you ever tried to read Mein Kampf? Put me to sleep about the time he bragged about the Nazi Party getting a mimeograph machine.