One of this guy's (many, many) claims is that a whole lot of his notes from primary sources were ruined in a flood in his office. The "dog" ate his notes! The Sernstein article is detailed and devastating. Maybe he and Doris K. Goodwin could get together and co-author something.
BTW, one more claim is that the Emery cleaning crew threw out a lot of the author's damaged notes. I teach in a university. Cleaning crews in universities are taught NOT to throw away anything that is not either in a wastebasket or shredded.
Too many professors are messy and leave papers around all over their offices that they intend to keep, for the cleaners to decide to throw out miscellaneous stuff from offices without express permission such as a note on a pile of papers plainly saying "Cleaning Crew: Please discard".
This is a pretty common rule in universities.