> If that is the case, then copyright holds no weight any more. I should be allowed to train an LLM on decompiled firmware (say, Playstation, Switch, iPhone) in countries where decompilation is legal - then have the LLM produce equivalent firmware that I later use to build an emulator (or competing open source firmware).

It's funny you mention that, because one of the biggest fair use cases that effectively cemented "fair use" for emulators is Sony Computer Entertainment Inc v. Connectix Corp.[1] where the copying of PlayStaion BIOS files for the purposes of reverse engineering and creating an emulator was explicitly ruled to be fair use, including running that code through a disassembler.

[1]: https://en.wikipedia.org/wiki/Sony_Computer_Entertainment,_I....