I would guess that's not the case, but rather the memory was corrupt, or that the playback system wasn't completed when the game was on demo.
Take Smash Bros. Brawl, for instance: Replays can be corrupted, and desync the character on screen from the button presses, resulting in off-the-wall replay matches that do little to resemble the saved fight. Couldn't this just be the same thing as that?
After all, I'd think if there's any sort of meaningful AI to beat levels, you could pass the control right back to Super Guide just about any time you wanted to, and it could continue on through the stage, if such a thing were possible.