> It does not mean "as long as you never read the original code, whatever you write is yours"
I think there is precedence that says exactly this - for example the BIOS rewrites for the IBM PC from people like Phoenix. And it would be trivial to instruct an LLM to prefer to use (say, in assembler) register C over register B wherever that was possible, resulting in different code.
As long as you never read the original code, it is very likely that whatever you write is yours. So I would not be surprised to read judges indicating in this direction. But I would be a little surprised to find out this was an actual part of the test, rather than an indication that the work was considered to have been copied. There are for instance lots of ways of reproducing copyrighted work without using a copy directly, but naive methods like generating random pieces of text are very time consuming, so there is not much precedence around them. LLMs are much more efficient at it!
Different but still derivative
Well, I am not exactly a hotshot 8086 programmer (though I do alright) but if I was asked to reproduce the IBM BIOS (which I have seen) I think I would come up with something very similar but not identical - it is really not rocket science code, so the LLM replacing me would have rather few alternatives to choose from.
I believe those are actually separate matters. A proper clean room implementation on the one hand, and the question of whether or not a particular outcome was a foregone conclusion on the other. I don't recall where I saw the latter but it might have come up during Google v Oracle?