I got the impression from Richard Rhode's books that Szilard, for all his ability and achievements, was a pretty pretentious 'know it all' with a (possibly justified) powerful sense of his own importance. This article kind of hints at this nature as well. I think it's largely this that has prevented his name being perhaps as widely known as Oppenheimer, Teller, Fermi etc when one thinks of the Manhattan Project, as those who retell these events often appeared not to like the man particularly much. Fermi of course chose never to work with Szilard ever again.