It's somewhat more complicated given that much of the significant work passed on by Klaus Fuchs to the Soviets that they acknowledge was responsible for the first Soviet fission bomb was Fuchs own work .. he shared with the British, the Americans, the Canadians, and the Soviets .. who were all ostensibly allies at the time.
The Soviets had the first flying object in space, the first animal in space, the first human in space, first spacewalk, first woman, first space station. I doubt those plans were all in the US, and if they were, the US didn’t use them.
This is complete moral bankruptcy. You're saying it would be better, rather than developing excellency, to instead become a parasite. I understand that in a world where winning is all that matters, this might be a viable strategy... For a while, until everyone adopts it or you otherwise kill your host. But this is not what being a human is about. I wouldn't want you near anything I care about
Moral bankruptcy is probably a bridge too far here: in weapons, especially with weapons of such power, espionage should be expected. Besides, upon first use you advertise the possibility and that alone will be an enabler, an existential proof that something is possible but you don't know how is a completely different story than groping in the dark while wondering if a thing is possible or not. Any kind of lead will surely be sooner or later be squashed. Note that nobody thought that using the patent system to get IP protection on the Atomic Bomb was a good idea: our friendly ways to establish who gets to make bank on an invention like that would simply fail and would actually pass valuable information to the perceived opponents.
When applied to medicine that same attitude becomes parasitic: you may be able to make much more money by restricting the distribution of the knowledge that could save people or prevent their suffering. This is where Martin Shkreli and other such characters come in to play.
