It certainly seems to be a purely emotional reaction. How many actual moviegoers would have really known about the script, much less the plot? And even for those who do know the plot, consider how many people see movies based on books they've read. Really, there's no rational reason to cancel (or postpone) the production. I certainly understand the emotion - the feeling of betrayal. But the decision seems ... irrational to me - even if he doesn't rule out going forward later on, after the book is published.