They didn’t expect it to happen because of all of the landmark rulings in the past that emulators are inherently not illegal unless they provide bios to the end user. The only reason why Nintendo is acting now instead of years ago when Yuzu first hit the scene is because it’s in basically a fully working state now and they somehow verified that 1,000,000 people downloaded TOTK. I suspect far more copies of BOTW and Mario Odyssey were downloaded prior.