>>13563559See
https://www.discovermagazine.com/the-sciences/chain-reaction-from-einstein-to-the-atomic-bomb"Despite helping to spur Roosevelt into action, Einstein never worked directly on the bomb project. J. Edgar Hoover, the director of the FBI even back then, wrote a letter to General Sherman Miles, who initially organized the efforts, that described Einstein’s pacifist activities and suggested that he was a security risk. In the end, Einstein played only a small role in the Manhattan Project. He was asked by Vannevar Bush, one of the project’s scientific overseers, to help on a specific problem involving the separation of isotopes that shared chemical traits. Einstein was happy to comply. Drawing on his old expertise in osmosis and diffusion, he worked for two days on a process of gaseous diffusion in which uranium was converted into a gas and forced through filters.
The scientists who received Einstein’s report were impressed, and they discussed it with Bush. In order for Einstein to be more useful, they said, he should be given more information about how the isotope separation fit in with other parts of the bomb-making challenge. Bush refused. He knew that Einstein didn’t have and couldn’t get the necessary security clearance. “I wish very much that I could place the whole thing before him and take him fully into confidence,” Bush wrote, “but this is utterly impossible in view of the attitude of people here in Washington who have studied his whole history.”
Thus the scientist who had explained the need for a bomb-making project was considered too risky to be told about it."
He never asked to be a part of it
