There is absolutely nothing untoward about making a for profit emulator. That is not illegal, and never was. As for the keys, it is ultimately the user who has to circumvent copy protection and extract one from a device in order for the emulator to function. Yuzu did not feature any copyrighted content and Nintendo didn’t suggest that as a cause of action. They claimed that Yuzu facilitated piracy, which is rather nebulous. Nintendo constructed an idea of secondary liability which would’ve been interesting to see argued in court, but this kind of lawfare is both expensive and risky so Yuzu’s team rightfully decided not to play that game. That doesn’t make Nintendo’s actions justifiable and consumers are free to exercise their own discernment and moral compass.
As far as I’m concerned, when I purchase a Nintendo Switch, I am also purchasing a license for any and all software contained within it, which includes any and all keys it may contain. If those keys are necessary in order to allow for interoperability with other software I might be using then guess what, I’m extracting them, and there’s a readily available DMCA exemption for that purpose. That’s not “piracy”, I am one user, I’m not distributing content that I already own to other users unless you want to argue that I’m distributing it to myself, which is stupid. If I want to play my copy of Doom on a toaster then I will, the same applies to TOTK. If Nintendo doesn’t want me to play TOTK on a device other than the Nintendo Switch then maybe they should A) optimise their software better or B) release hardware that doesn’t make a toaster the preferable option.
All of this contrarian nonsense on behalf of a multibillion dollar mega giant of a company really rubs me the wrong way. In order to use Yuzu at all the user had to have a Switch to extract a key from. If Nintendo wants to claim that keys were shared illegally, they can go for it and have fun chasing people who are doing that - that’s their property and shouldn’t be shared. If they want to chase game pirates, more power to them - their property, shouldn’t be shared. Chasing after developers of an emulator as a catch-all solution is the wrong way to go about it.