“YouTube user The Phawx posted a video showcasing how well the Steam Deck can emulate the Nintendo Switch, and it was soon taken down on copyright grounds.”
A review of how well a $400 handheld runs an emulator is not piracy. Nintendo filed a copyright claim and YouTube pulled it anyway. The Switch just outsold the Wii, so this is not about lost sales. Nintendo uses takedowns to scare people off the idea before they try it.