Agree completely, the title is misleading. I was amazed by it by just watching the video, but this is actually a fan project. Which is cool, but not a prototype of the original game as the title implies, or something that should be "recovered".

Reminds me of a ROM-hack for Zelda: Ocarina of Time from a few years ago, that was presented in the release video as using unused assets and storyline from the game itself, when it was actually almost entirely new material. A great technical achievement, to be sure, but somewhat dishonest in its presentation.