Every leader is also a follower.
From the chairman of the Joint Chiefs of Staff to the newest cadet staff sergeant, everyone with a leadership position is someone else's follower. The role depends on the situation, and it is important to behave appropriately. You are required to be appropriately respectful of them. The flight sergeant is a cadet master sergeant, so you are an element leader. The first sergeant is giving all of the NCOs drill command practice, and chooses a cadet staff sergeant to lead the flight in drill.