Yes, but the situation is a bit different -- the majority of UNIX rights owners were actually promoting open standards through initiatives like POSIX, X/Open, s

Yes, but the situation is a bit different -- the majority of UNIX rights owners were actually promoting open standards through initiatives like POSIX, X/Open, so the re-implementation did not violate the copyright. As far as I know SCO's suits were not about interfaces of any kind, and the Linux kernel uses C standard library and other posix compliant libraries as an interface.