I don't get too bent out of shape about it either way. Sure, atom age better describes post-war thru at least mid-50's (though arguably the hallmarks of silver age storytelling don't really come along until FF#1; much of the DC hero revival stuff has no new tone to it to speak of) but arbitrary cut offs don't neatly describe every book in a given year. For example, Adventure Comics from 1946 reads more GA than Atomic in its substance.
People love to quibble about this stuff, and it's interesting, but comics evolution is more of a continuum, it seems to me.
Then again, growing up in the '70s, before it was declared the Bronze Age, it didn't strike me as necessary to have an Age label to encompass every year of comic history. WWII was Golden, Silver was the hero revival. The interim and the new stuff were cool and different on their own, absent a label.