So not only did you not provide any evidence that people are more prone to cheating now than before, but your own cited link states that cheating rates in college have stayed the same over the past 50 years.
Nothing wrong with that, they could be a great DM. However you should mention that the MM and DMG are SUGGESTIONS and any hint that he is trying to use them as books of law (but kobolds can't breath fire!!) will not be cool.
I'd ask him whether he prefers to be surprised by the monsters, or spoiled by reading the MM? I suggested to my players that they not read the MM, for the sake of their own enjoyment! I'd certainly love to play through a 5E game without knowing what's coming at me.
If the player says he doesn't care, well he's the worse for it IMO. Simply let him read the MM and not be surprised.