Thanks for posting this.
I too am a Heinlein fan, since I was a teenager.
I note that this story was written in 1949, and certain details it contains about atomic bomb operation may have been classified, or at least are schematic representations of information that was probably classified at the time, thinly obscured.
Other Heinlein stories of that time contain further details of atomic weapon design that IMHO reveal that Heinlein was privy to things he probably shouldn’t have been.
He did have a Navy background, and so might have been let in on some inside dope through those contact. Also, IIRC, he was for a time in the orbit of Jack Parsons and the other members of the GALCIT rocket research group that later became Aerojet General, so he might have heard some details through that pathway.
The story’s message is as valid as ever, but the trappings and color of it are very much a product of their time, and amusingly so.
Heinlein fan from way back.