I'm in the production/entertainment industry so deal with many of these issues on a detailed basis, but I've learned that there are many times when there isn't a contractual obligation to do something, but for the sake of maintaining a positive relationship for future projects, an estate holder is sought out to make sure they have no issues with it.

Simply put, we don't have access to the contracts and agreements in place between the Rigney Estate and Tor's publishing entity, so we really can't read into the specific details of a public statement. What I've learned from my experiences is to let the signed agreement do the talking and not really put as much weight into public statements. After all, the details of the contracts are sealed by attorney/client privilege, and unless you approached them with an offer, there would be no reason for them to be told of rights limitations.