That's literally not how anything works.

I think it’s more depressing that the writers of late 1940s or early 1950s Disney comics didn’t understand that as long as you have pencil technology, preserving the “formula” to make an atomic bomb does not require effort.

I think that is a view with the knowledge of hindsight.

In the 1940s and 1950s knowledge about how the atomic bomb was created and where as very limited. It wasn't until 1994 the primary archives of the Manhattan Project were declassified. Any public knowledge before the was limited to specific releases the government chose. The 40s and 50s were also well before the general knowledge about how nuclear weapons work and that the difficulty is fuel refinement and shaped charges. So the general knowledge of the public (and comic book writers) were probably limited to just chemistry. The basis of what we commonly know as C-4 plastic explosives (used in Hollywood action movies all the time) wasn't even invented yet until 1950 (Semtex). So new chemistries of explosives were still coming out in the contemporary day of these comic book artists. Its not a stretch to for the artist to think that the atomic bomb was just another type of formula.

Or more realistically, the "formula" was just the word chosen for the Macguffin used to move the comic book story forward.

Maybe that was the only copy and the “enemy” didn’t get to read it yet?