If there is one thing I've learnt for sure from all the random forum posts used in this trial, it is that "IANAL" is a good thing to say!

Nonetheless, I don't think the clean-roomness or otherwise of an implementation has an impact on this. Otherwise someone could copy music by listening to it and replaying it.

Like you said: the copyright is on the text, pattern and structure of the code. But it doesn't matter how it was replicated.