But they are not going after the piracy. They are going after the legitimate method of playing switch games on your PC. I'd argue that MP3 player apps are nowadays mostly used with pirated music, yet I don't see anyone going after them.
Well, there's a bunch of places where that's not true. Then it's a question of morality, although that usually gets unfairly asked of the individual but never asked of giant mega corporations.
It's illegal to pirate games. Being able to emulate things you purchased is a convenient scapegoat for people to pirate games.