I'm not the right person to ask the question to. The appointment system is an executive function the Prime Minister and the Clerk of the Privy Council exercise. These are Governor in Council appointments, and the usual explanation of why somebody is moved is to ask why the vacancy was created in the first place. There is a domino effect, such that people get assigned to other jobs because there is a vacancy to be filled. There is a relatively small pool of people who are ready to be deputy ministers of departments, and they get moved around to other assignments.
It's beyond my control how those things happen. I'd be happy to work in a different kind of system. I work in the system I'm given. You'll just have to accept my good faith to do what I can during the time I'm responsible for the department.