The issue is the whole “circumventing encryption” thing, which is what led to the infamous win for Nintendo. The judge ruled that by using an official Switch’s encryption keys, the emulator was primarily designed to circumvent encryption and sided with Nintendo.

I agree that it shouldn’t be violating anything. But clearly, Nintendo managed to convince that judge. And since courts look at precedent and case law when issuing rulings, any future rulings will likely go the same way unless a higher court overturns it.