I think it is an article of revenge because of William's insistence that the tabloids don't publish pics of Catherine at the moment.
I doubt that unnamed "estate worker" has any insight into the decisions made at the main house. Probably they really changed the film but I doubt on William's orders, but maybe because they couldn't get the copy of Skyfall and had to take Twilight instead? But I can imagine that someone with no real knowledge might assume that it was because William had already seen Skyfall, then goes to the pub and blabbs to journalists who then write the story, which is published in order to show William what can happen if he doesn't give in to the media....