Nintendo has a horrible history of shitting on its fans and projects such as these. In all probability the modders are actually inadvertently (I haven't checked) falling into Nintendo's trademark trap on the Gameboy. The Nintendo logo it shows at the start is a check that enables the boot of the game... and is an asset that must be present on each cart. That means if the logo is displayed... they can sue for trademark infringement. If not then they are exploiting the hardware- and we know what happens from there, unfortunately.

This is a cool project and I hope it does well but Nintendo is a shit company that doesn't deserve the fanfare they are given.