Reading the takedown it sounds like just having the decryption code itself counts as "circumvention". I feel like emulators would be a lot safer if game decryption was a separate codebase. Then the emulator would be free to develop while Nintendo plays whack a mole with tiny easily remade decryption repos that just take your key and the file and decrypt it.

Hell ryujinx could even detect that you have the decryptor installed and automatically call it when needed, or it could be bundled during packaging but separate in development like how Bluray decryption is distributed in a separately library but can be used by for eg. VLC.