You can read that page of Trachtenberg’s book in Google Books, as I just have, by googling Marc Trachtenberg Szilard. Trachtenberg misunderstood what Szilard wrote in the references he cited. I just reviewed those also. 

Leo Szilard has been my research focus for decades. 

Is this an April Fools joke? This article claims that Leo Szilard supported a nuclear first-strike on the Soviet Union. Nothing could be further from the truth. I would know.   Gene Dannen