Deathmatch: Alan Dean Foster vs. The House of Mouse!

Apparently, when Lucasfilms sold the Star Wars rights to Disney, the sale included the rights to all of the books, including Alan Dean Foster's novelization of Star Wars: ANH and _Splinter of the Mind's Eye_, the first SW tie-in novel. When Disney bought 20th Century Fox, the sale included the rights to ADF's novelizations of Alien, Aliens, and Alien 3.

Disney has not paid him any royalties even though all of these are still in print, claiming that "they have purchased the rights but not the obligations of the contract."

This is probably going to get ugly. I have to say I am not impressed by Disney's argument here--Foster's contract apparently includes assignees, and AIUI that's Disney's status wrt the contracts between Foster and Lucasfilms/20th Century Fox. Anyone with a real legal background want to weigh in?