"Novell also announced it has entered into a definitive agreement for the concurrent sale of certain intellectual property assets to CPTN Holdings LLC, a consortium of technology companies organized by Microsoft Corporation, for $450 million in cash"
Novell's waiver got a whole load of SCO's claims rejected. Hands up: who wants to see that particular can of worms reopened?
I love the way GPL renders toothless some threats.
And the claims Linux code was a copy of Unix were completely refuted, IIRC.
Also, I'm not sure if the copyright question was ever full ruled upon, since SCO never had standing to sue over something that they didn't own. I didn't follow all of the SCO rulings, but since they didn't own any UNIX copyrights, that argument could have just been moot.
It's quite an unambiguous grant. Not only patents, but of whatever other instrument that could be used to remove the right to redistribute verbatim or modified versions in accordance to the rest of the license.
It was never tested on court. This can be a reason.