I think your conversation with him could be professional, but you just need to point out You’re the leader and they gotta follow your direction and he doesn’t wanna be on board with that then he needs to find some other role which means leave your group and then work with management above you to make that happen but I’m assuming you can do the reviews for him and then penalize in that manner if you don’t have that ability to give them a poor review then something else is structurally wrong and where you are in that organization.