“the military (the Air Force specifically) took it to determine if it had any value re: national defense.”
That is generally true.
However, we now know for example in the Trinity case, that it was the Atomic Energy Commission that seized and hoarded the information.
The whole notion of “national defense” in this context is a caricature of human stupidity.
If these things are a risk to one country they are a risk to all—there is nothing “national” about it!
When the government (Air Force, AEC, or other) said “national defense value,” I think they meant value in the sense of using what we had in our possession as a weapon or as an aid in developing weapons against our adversaries (Russia, China).