I don’t think that’s a good argument. In a more general case, if you didn’t pursue your rights 10 years ago that doesn’t mean you can’t get your shit together and do it today. Maybe you’ve lost some of what you deserved but you still should get future benefits.
As for statue of limitations, if it keeps happening today then it doesn’t matter when it started. They could only talk about things that happened in the past year - it’s still being hosted and shared.
To be clear, I’m not taking Nintendo’s side, all efforts to preserve these games are amazing and I love to see everyone keep it up :)
If someone shared ROMs 20 years ago and stopped, Nintendo wouldn’t be able to do anything about it today. The statute of limitations does apply.
But if someone started sharing ROMs 20 years ago, and continued doing it every day until today, then that means they shared ROMs yesterday. The “crime” still happened yesterday.
Edit: but they care a lot more about preventing it from happening tomorrow.