Did you miss the part where this was a contract issue? Where the author of the book said, literally, "Yeah, Gravity is a great film, but it's not based on my book"? She's trying to argue that a contract she made with one company would somehow jump across multiple acquisitions, mergers and organizational changes and begin binding a different company that made a movie she admits wasn't based on her book. And that's why it comes down to contract law, and contracts do not represent an easy, straightforward, intuitive body of law.
You don't particularly have to like the way that stuff works, but the simple truth is that changing it to make it work the intuitive and desired way in this particular case would probably result in many more other types of cases suddenly coming out in ways you wouldn't like.
You don't particularly have to like the way that stuff works, but the simple truth is that changing it to make it work the intuitive and desired way in this particular case would probably result in many more other types of cases suddenly coming out in ways you wouldn't like.