The producers of the movie should sue him, maybe under a tortuous interference theory. His deliberate actions have caused them to lose potentially tens of millions of dollars. Though, you could mount the defense that they knew full well that King was a deranged leftist when they engaged him and should have expected him to do something like this.
Yes they should. Despite King ever being a great writer (which he was once), he deserves none of his wealth and should be sued in to the ground.
No leg to stand on. How could they have not known King was a lunatic TDS sufferer?