According to this: https://blog.ipleaders.in/star-wars-is-owned-by-disney-walt-...

> Disney bought the operating businesses of Star Wars, Indiana Jones, and Lucasfilm in live-action film production, consumer items, video games, animation, visual effects, and audio post-production as part of the agreement. Disney also bought Lucasfilm’s entertainment technology portfolio.

If this author’s work wasn’t part of that buy…I’m not sure why Disney would be on the hook for the royalties.

Canon is probably mentioned in the contract re Lucas. He is certainly forbidden from releasing new content that is in any way connected to SW. He is also probably under some sort of obligation not to do interviews or release statements about what is and isn't cannon. Hypothetically, if Lucas came out and said that Episode II was a mistake that shouldn't be cannon, or admit that the existence of the Christmas special, Disney would go after him for acting in bad faith.