John Waterbury's book reviews in Foreign Affairs

I was stunned really to read the negative book review of Shadow Wars by Christopher Davidson in the latest issue of Foreign Affairs.  I was surprised because Waterbury frustratingly never writes negative reviews like that, even for the most lousy books (politically and academically).  Yet, he reserved a particularly nasty review of Shadow Wars.  He even claimed that there is no original materials in the books when there is plenty:  (Clinton's emails on p.284, 290,297, 298, 299, 301, 305, 308. E.g DIA docs released to courts: 305, 420, 421, etc.) In fact, Waterbury was alerted to this by the publisher and the on-line version of the review was amended. But why did this book bother Waterbury so much? Or does the question reside in his book Egypt of Nasser and Sadat: the Political Economy of Two regimes?