From a reader:

Thought your remarks on pegler were pretty accurate. So i thought this might interest you.
According to Arthur Schlesinger’s ‘Robert Kennedy and His Times’, Pegler was a “chum” of Joseph P. Kennedy. Seems RFK, Jr forgot to mention that.
Pegler is also quoted elsewhere in the book so I guess Schlesinger is also a fascist-rascist-whateverist too!
(check google books)