That was what was alleged; it has nothing to do with the outcome.
McGinniss agreed to write a book about MacDonald's attempt to clear his name, after he was accused of killing his pregnant wife and two small children. The resulting civil trail showed that McGinniss had regularly deceived MacDonald to ensure his protagonist kept talking for his book. He also told MacDonald not to talk to other journalists interested in his story.
Today, a trio of authors says that the unscrupulous McGinnis portrayed in "The Journalist and the Murderer" is very real. They allege that the bestselling journalist leaked a manuscript of their tell-all Palin book - The New York Times bestseller "Blind Allegiance to Sarah Palin" - to destroy any chance it would be published and compete with his own forthcoming Palin exposé, "The Rogue." McGinniss admits he received and distributed the manuscript, but maintains that the idea that he did so to hurt the authors' chance at publication is absurd because the authors were nobodies,
McGinniss is a dishonest pig.