Thats what I thought initially as well
But then they introduced the move Bounce, which would seem to be something like that (jumping and attacking with a flying type strike).
I dunno, maybe they just gave it to Dodrio because they figure birds should fly, regardless of whether they are "supposed" to be flightless or not.
And they can't remove the capability to learn certain moves any more, because it would cause issues when trading (since Diamond/Pearl are going to be compatable with Ru/Sa/E and FR/LG)