Nah, there's no circumvention here, on Yuzu's part. There
may be parties involved in circumvention, but the emulator neither aids nor publishes any aid for that. The emulator REQUIRES a user to first have a legitimate copy. If the user illegally obtained that copy, they didn't obtain it via Yuzu, and they didn't use Yuzu to get around the encryption that is in the file. The emulator is just using the key on the file, the same way any application - including the Switch OS - has to. That's not "circumvention", that's "usage". If the key should not be able to be collected, for use on the file, then it's not the Yuzu emulator that collects the key. It's whatever ROM dumping/packaging solution a bad actor is using.
If it ever made it in front a jury, it can be summarized as a big company trying to sue a little company out of existence because the big company doesn't like that the little company is executing the big company's code. But, unfortunately for the big company, executing someone else's code - even without their permission - is not illegal. Nintendo has the resources to sue torrent hosts and take on individuals involved in sharing networks. They have the resources to find the problem and fix it. But they're not using those resources to solve the problem; they're using those resources to scare lawful citizens into inaction because that's a cheaper target. There should never be a legal reward for that kind of scheme.
But, honestly, this should never make it to trial. There are zero merits for argument, here.