I've just read the whole arguement between you and Nomad and reviewed the episode you have been talking about. And Groxhugger, i'm sorry but there is no airbending abilities shown by the Yuyan.
This 'gliding' you see is not there is just something you have interpreted because you want to be the first to discover something and are doing everything in your power to try to bering evidence into this baseless conjecture. And even if there was some 'gliding' then it would simply be an animation error.
Sozin made his intentions clear he wanted to expand the Fire Nation empire and to stop the Avatar from threatening him.
Solution: Wipe out the Air Nomads. He never would he have allowed any airbender or non-airbender citizen (unlikely that may be), because even if they tried to brainwash this new Avatar the Avatar Spirit would connect him to his ancestors and show him the truth.
I'm sorry you had to put up with this Nomad, it seems he is sturbonly sticking with this.