Well, that hit the screw in the head, you reached the right conclusion but with the wrong idea.
There are a couple of things that people need to understand about developers: first of all, we are arrogant (as
Uncle Bob says), we create things out of nothingness, we are able to make machines do what we want. We have control over things. I don't say we see things like Neo in the Matrix but we see deep beyond the software, we know how many or all the things are done and we are able to notice how to exploit them. So, after being so recognized in the development community starting from scratch as a contributor anonymously is really harsh. The compensation is not always monetary, it could be prestige, being able to say "I did a thing" (btw go check his channel, he's great).
The second thing is that a passionate developer loves what he does, we return home and continue coding, we code on weekends out of passion, not necessity. So while the idea of being forced to stop developing something you created and worked on for so long is harsh, the idea of being sentenced to not being able to use a computer or develop software is hellish. I cannot picture myself working as anything else but a developer, and I think those guys felt the same. The risk is just too high. Not even mentioning that having your name appear in a federal case isn't resume material.
So, unless they are teenagers and utterly dumb they won't be back at emulating Nintendo consoles (I would risk to say, they will never emulate again) unless they want to end like Gary Bowser.
Regarding Ryujinx implementing Yuzu code, the licenses are not 100% compatible. Ryujinx is licensed under MIT and the code they were to pick is licensed under GNU GPL3. So even if they could they shouldn't if they want to keep their contributors. It's more a matter of ethics than legality as the GNU GPL3 yuzu code is effectively dead and nobody would sue them for including it.