Yuzu was charging for early access to their emulator, which is what prompted Nintendo action.
Ryujinx doesn’t seem like any legal action was taken, sounds like the creator was given a chunk of cash by Nintendo to take it down.
I hate Nintendo, but you gotta keep the facts straight
They also shut down Yuzu forks using the DMCA. If they paid Ryujinx’s dev it was the equivalent of the Mafia bribing a judge while waving a picture of his family.