Isnt the treadmill going to cancel out the engine thrust?
I mean the debate is a treadmill moving at the same speed as the plane.
If you are running on a treadmill and someone pushes you, yes you will go forward, but not clear across the room.

Engine thrust may cause the plane to go faster than the tread mill, and will just move it forward off the treadmill, if the treadmill does not speed up.