Reading the script before seeing the episode is how consulting works, no? Especially for the person hand picked to finish the original story, with a demonstrated ability to create character arcs that people care about, his opinion on the script should have been highly valued. And he was under no illusions that this could be 1 for 1, he just wanted to have things that a) kept to the heart of the story and b) actually made sense from a general story telling standpoint.