I have no clue whether the proposed approach works, but there's a pretty coherent model that explains how it could, no schizophrenia needed: They are competent people in a cult.

Being unable/unwilling to diss Dear Leader even when it's advantageous to do so is very typical cult stuff. In fact, it's sort of why cults are dangerous. They compel people to do maladaptive things in service of the "ideals" of the group/leader.

This applies both to the spy directly (perhaps they would personally be unwilling to say such a thing), but also to their entire chain of command. Cults by their nature are not good at passing nuanced instruction like "you can say bad things about Dear Leader under these circumstances." Just because you're willing to diss KJU to get in the door doesn't mean you know your entire chain of superiors are cool with it.

You are talking about North Korea attackers from a theoretical point of view. For many people dealing with them is just a normal part of work. It's not an unknown that needs to be worked out logically from an armchair.

I'm saying this as someone who personally chatted with a North Korea persona that later tried to drop exploits on people, and the persona belonged to hacking group with at least one 50 million dollar heist. I've also seen the screenshots on many chats with North Koreans.