Of course the demo would be built off the gameWell its either build the demo off a build of the game or build the demo from scratch. They chose to make it off a build of the game. Everything is probably not included in the files though.
I'll still keep a positive attitude towards it anyways. If there isn't any new mega evolutions, oh well. :\
But you don't need all of this junk in there. You don't need trainer data for trainers that never show up, map data for routes that aren't even made, dialog for portions of the game you wont see, pokemon data for pokemon that don't show up at all, move tutor data, trainer artwork for things not in the game etc