“We actually had written a scene with him in it that was a flashback kind of thing,” Abrams told AMCtv. “But the truth is, it didn’t quite feel right. The bigger thing was that he was very vocal that he didn’t want to do a cameo. We tried desperately to put him in the movie, but he was making it very clear that he wanted the movie to focus on him significantly, which, frankly, he deserves. The truth is, the story that we were telling required a certain adherence to the Trek canon and consistency of storytelling. It’s funny — a lot of the people who were proclaiming that he must be in this movie were the same people saying it must adhere to canon. Well, his character died on screen. Maybe a smarter group of filmmakers could have figured out how to resolve that.”
So there you have it. William Shatner is the reason William Shatner doesn’t make a cameo in the new Trek.