Nah. From Nintendo's position, you don't "own" the game. They do. All you bought is a license to play the game on a Nintendo approved console. By ripping the game from the switch dump, you are violating the license you bought by copying their software without permission.

From a practical perspective, fuckem. Your paid money to play the game and if you decide to play it on something else you own, go nuts.

it's legal to dump that game to a PC and play it on a Switch emulator, right?

Depends on where you live. Copyright law varies significantly from country to country.

In the USA, section 117 of the copyright act lets you create a copy for archival/backup purposes only. What I'm unsure about (and don't know if there's any relevant caselaw) is whether bypassing copy protection to create the copy violates the DMCA.

The equivalent Australian copyright law explicitly states that you can use the backup copy instead of the original one. The US law doesn't (all it says is that you can make an archival copy, not how you can use the archival copy), so it's a grey area.

Both laws are for "computer software", but you could easily argue that a video game is computer software.