If I, a human, read the source code of $THING and then later implement my own version, that's not a "clean-room" re-implementation. The whole point of "clean-room" is that no single person has access to both the original code and the new code. (That way, you can legally prove that no copyright infringement took place.)
But when an AI does it, now it counts? Opus is trained on the source code of Clang, GCC, TCC, etc. So this is not "clean-room".
That's not the only way to protect yourself from accusations of copyright infringement. I remember reading that the GNU utils were designed to be as performant as possible in order to force themselves to structure the code differently from the unix originals.
What life does one lead to be this sore in life