Actually, I think EA is generally pretty well-balanced in the attention and interest in the Manhattan Project. There is an n of one for world-ending inventions, and most researchers and historians working on it are well aware of how AI and biorisk would not happen the same way. 

However, the interest in the Manhattan Project itself is too high relative to interest in the rest of the Cold War, specifically the first two decades after the Manhattan Project. The Manhattan Project itself was seen as a bomb built to win WW2 and, to a lesser extent, a source of power plant fuel. When Oppenheimer said "Now I am become death, the destroyer of worlds", he was imagining another WW2-style carpet bombing war (and so was the rest of the military brass watching the test). Building arsenals of atom bombs also directly emerged from the WW2-idea of carpet bombing by swarms of fighter-bombers..

It wasn't until a few years after the Manhattan Project that foreign affairs and military doctrine started bending to revolve around nuclear weapons, as well as intense pro-atom sentiment (such as the idea of a transformative technological revolution from effectively getting unlimited dirt-cheap energy from a small number of uranium mines). 

The Cold War, specifically the first two decades, tell us almost everything there is for us to know about the history of policymaking on x-risk technology. Policymaking during the Manhattan project, on the other hand, was totally determined by WW2 norms, technology, and paradigms that are almost completely irrelevant to the modern policy environment.