WaPo doesn't seem to understand that in a world of ebooks and "search inside the book" Amazon pages, you don't need to look names up in an index to see whether and where they appear in a book.
I suspect that if there's no index in this book, it's to save printing expenses and because they wouldn't want anyone to assume that if a particular name isn't in the index, it isn't in the book. Now, you might say, but maybe Amazon won't have "search inside the book" for this particular book, and if people want to do a search within an ebook, they'll have to buy the ebook, so more books will be sold. But that assumes there are cheapskates — among the super-busy Washingtonians — who would go to a physical bookstore, find the actual paper version of this book, and look up names in an index. Anyone who cares that much would just download the damned Kindle edition from Amazon, which would take about 10 seconds. The search would be accomplished in well under a minute. Even if it's overpriced at $12.74, what is your time worth? And by "you," I mean some Washington entity who is important enough to imagine he'd get mentioned in a gossipy book by a NYT reporter, and yet not important enough not to care.