Whaddup Wid Upton?

A recently revealed letter from Upton Sinclair reveals that while he was hammering home the cause of Sacco and Vinzetti, he was aware of their guilt through an admission of the attorney for the two that they were guilty and he had framed alibis for them. All for the cause!
What next, a revelation that the Rosenbergs were actually involved in espionage?
Ah, History. Such a mix of fact and legend.