There's more to copyright than the code + the Switch came out in 2017, so even if 100% of everything they did today was via LLMs (I'm sure it isn't) and this line of thinking applied to all of it then it still wouldn't be relevant.

Also the focus seems to be on bypassing "technological protection measures" portion of the DMCA, which is much easier to go after than the code. Decomps are much more focused on purely the code angle and, for now, still don't seem to be in the focus of these attempts (I assume because it's harder to go after with the same kind of claim, but really only Nintendo will know why they haven't tried yet).