Floating Seat Technique

Elizabeth Tinnan uses and teaches a technique she created called a "Floating Seat" this can be seen in the action of the legs as she rides. The idea is to keep the upper body as steady as possible to make aiming and shooting the bow easier. This is not the commonly accepted best practice for rider balance and biomechanics. Do you think this technique is effective for maintaining a balanced posture? Do you think its effective for horse archery?