This book, because O’Brien reveals many times throughout it that it is not factual, is fiction. This is especially supported by the fact that in his interview he emphasizes that he waited for many, many years before he wrote this book, so that the details wouldn’t cloud his thoughts and the meaning of the book. This, coupled with the fact that the book is written in such vivid detail must mean that much of it is made up. However, just because it is fiction doesn’t mean the book is devoid of meaning. In fact, it is quite the opposite. O’Brien writes the book so long after the war precisely to get at the meaning of the war. Other than this fact about writing the book a long time after the war, much of the interview is not terribly informative about the meaning of the book.
The notion that fictional stories are more meaningful than fact-based novels is supported by the events of the novel The Life of Pi (I’m not sure how clear the movie makes what I am about to say). In this book, we see Pi tell two versions of the story of him surviving after a boat wrecks in the middle of the ocean. One is completely factual, and the other is essentially the same as the factual one, with animals substituted for humans. And it is the story that is fake that is the meaningful one, because it is the one that sheds light on how Pi’s experience actually felt.
Similarly, this is why O’Brien waited so long to write the book. He wanted to determine the meaning of the war from an objective perspective, so that he could get at the meaning in his book. Then, he filled in the holes in his story that had developed through the years to retain this meaning.