You don’t need a McCrystal ball to see an embedded hack is a bad idea
What was in it for him? He’s already been promoted by the President. Admittedly, he has some issues with the President and the White House gang, but not even a man this thick would have consciously set out to change their attitudes and behaviours through a magazine.
You also have to ask if the General had never heard of the scorpion and the frog. The apocryphal scorpion meets a frog on the bank of a river. Quite a broad river.