To be honest I hadn't heard of this guy before and I just googled his name to see what comes up, and his page on Amazon raises quite a few red flags with me if we are discussing him in terms of being "a reliable historian".

First of all, he is not a historian nor an academic. If we can trust the internet, he is a writer with a graduate Law degree, which says little to nothing about his credentials as a historian or even as an "investigative journalist" as his page describes him. I'm sure his books are quite entertaining if its your genre - with flashy book covers, promising to reveal to the reader the mysteries of some sinister historical plots. Lots of words to catch the attention of thrill-seekers and conspiracy theorists are thrown in "9-11 anthrax attacks", "biological warfare" etc. He has allegedly been published in numerous journals I have never heard of with sketchy names like "Cubanet". His books have been cited in other books with fascinating titles like "The biology of doom", written in all caps, and "The 80 Greatest conspiracies of all time"...

Amazon books by this guy include one about the JFK assassination which says in the title already that was a coup.

Just by his Amazon page alone, I would not order one of his books if I wanted a balanced study of CIA history in which the facts guide the interpretation, rather than the inverse. That said, I don't know him so maybe I am wrong. This is however how I would've made my choice on this writer.