This isn't about copyright, it's about whether the software's purpose is to break DRM. Ninty argued that Yuzu's primary purpose is to enable copyright infringement which is forbidden under the DMCA; both infringement of course but also even just building tools to enable it. The latter is the critical (and IMHO insane) part.

Now, all of that is obviously BS but Ninty SLAPPed Yuzu to death, so it doesn't matter what's just or unjust; they win. God bless corporate America.

The suyu devs do not understand the legalities behind why yuzu was shut down. It wasn't because of keys. It was because it could break copyright protection mechanisms, which is in violation of the dmca.

The suyu devs think that by saying, "we don't support piracy, you have to provide your own keys" is enough, and there's case law to show it isn't. Your project needs to be incapable of breaking copyright protection mechanisms with or without keys.