Hi! Sorry for responding 6 months after the original posting, but there’s a detail in this article that requires correcting: As some of your quotes from other sources make clear, the T.H.U.N.D.E.R. Agents weren’t WWII-era Golden Age characters, they were created 20 years later, in 1965; right at the height of the Silver Age of Comics.
This was also the height of the “secret spy agency” craze triggered by the James Bond films, which also gave us the Man from U.N.C.L.E., Nick Fury: Agent of S.H.I.E.L.D. and dozens of other tortured acronyms. So, pure 1960’s.
Thanks for listening!