They would also need to prove, in my mind anyway, that the 80 lines of code aren't there specifically to satisfy POSIX requirements (which ARE open) which, I believe, is the target Linus was aiming for.
Good point.
And anyway,
only 80 lines of code? Out of how many thousand?
Personally, I would find it extremely amusing if it turns out SCO is trying to lay claim to something which is in fact open source. ISTR MS also tried that one a little while ago.