Certainly the use of atom is no mistake, but I do not think Astro is a mere analogy for nuclear weapons or war the way Godzilla was. I feel like Tezuka uses Astro more for the exploration of racism than anything else; but I doubt Might Atom stands for any one thing.
Rather, Astro was done over years, and with one singular goal--entertainment! Sometimes Astro comes off as a very thoughtful comic, sometimes it is just good ol' fun. Personally, this isn't one I'd look too deeply into.