That’s not really his fault though, physics is physics, and he wasn’t really pushing for its creation as much as he was terrified that Heisenberg and the Nazis were going to get to it first.

I can't fault him for theorizing the atomic bomb. Its a weapon that can be used by anyone, and if it wasn't Einstein, its only a matter of time until someone else does it. Its better to get a jumpstart and protect the information, resources and weapons than to stick your fingers in your ears and do nothing, rather than let the capitalists and nazis get ahold of it first and maintain a monopoly.

Perhaps, though that was sent 10 years before he wrote his article on socialism, alot can happen in that time.

Also, regarding that letter, he seems to have written it not to promote building the bomb, but rather to emphasise precaution and 'watchfullness' in its inevitable development and subsequent use.