The problem with legal discussions on HN is that for every strained metaphor, you can make one in the other direction.
I buy some milk from Albertson's. Am I now responsible for their corporate debt? I buy _all of the milk_ from Albertson's. Am I now responsible? I buy all the milk, the veggies, the building that holds them, the delivery trucks. Am I now responsible?
The point is that it isn't patently absurd in the same way that the opposite isn't patently absurd.
I would imagine that Lucas owned the books, even if somebody else wrote them. And there is a royalty agreement, of course. But there is a possible context-free explanation that is at least logically consistent.
The way the company buyout example works is that the company sells all their assets, then you have litigation/bankruptcy proceedings that use the money to make employees and owners as whole as possible. Employee work products are owned by the company, there isn't some unbreakable link there by default (beyond some natural rights about being able to say you are the author). But in that model, of course, if there are a lot of useful assets, a lot of money is then in the bank to pay out the employees!