Nintendo is a conservative company with strong, well known brands (Mario, Donkey Kong, Legend of Zelda, etc.). I'd be surprised if they rolled over and let this slide.
I'd be doubly surprised if they ever open sourced anything.
I've always viewed 4chan as hardcore chaotic neutral. They're quite happy to find novel solutions to mathematical problems, DDoS people they don't like, openly work with leaked source code, create a new chat system (tox), troll celebrities... they don't care about good/bad, they care about whatever strikes them as interesting or fun. Which is... a very mixed bag:)
Be wary of doing this if you ever intend to contribute to projects related to Nintendo and the N64. Viewing this material will make you radioactive to projects that care about legal risk.
Eh, the community has already had leaks of similar consequences for 20 years. At the time, it devastated the community, but pretty much all emulators since have been based upon it in some way. The open secret behind emulator development is that it is often built on the backs of stolen material. The first popular N64 PC emulator, Ultra64, was a hacked up copy of Nintendo's PC emulator core.