what exclusive rights? There are no "exclusive rights to reproduce the copyrighted work". It's why emulators can't be taken down.
I see, I feel like your earlier language was claiming that the game itself could be legally copied with no issue, when what you're actually saying is that "building an emulator that can run an existing rom" is fine. Within that narrow scope, sure. Tho that's not really "porting" at all, it's writing a Switch emulator that is playing an illegal rom. If you are saying "porting a game is not illegal" as a catchall, though, that's obviously false, since the rom itself is an illegally obtained material.