Nintendo is one of the worst companies that always want to set an "example" about the DMCA. They don't realize they are fighting a battle they cannot win. Emulators are perfectly legal as long as the emulators don't contain any code that was in ownership from them.
That being said, I'm betting some of those forks were following the DMCA but Nintendo still shut them down. This is where copyright needs to be reevaluated.
I'm honestly not surprised they haven't gone after dolphin emulator since those devs contain the encryption keys to play the iso files.