[charcircuit]

The game is a copyrighted work, but so is the source code. The compiled code is a derivative work, and so is the decompiled code. Nintendo is not selling the source code, so arguing about sales in the market does not makes sense.

[EMIRELADERO]

The fair use analysis is done on the work as a whole, the Zelda game that's registered on the Copyright Office. Not the code only.