The people of the 60’s probably didn’t notice much because they were already surrounded by Roman mythology and motifs since the revolution.

In The Smithsonian there’s an odd statue of Washington bare chested wearing a toga , looking like a classical god. The founding fathers were highly influenced by Roman philosophy.

I’m told that Protestants are more offended by appropriation of Christian motifs than they would be by appropriation of pagan symbols.

The planets were already named after the Roman gods, and when more planets, moons and asteroids were discovered with telescopes, the tradition of using Greek and Roman names continued for the most part with the exception of some moons being named after characters form Shakespeare.

The Greek and Roman religions , being polytheistic, have rich source material that lends itself easily to cosmic subjects. Artemis makes total sense on that account. Other than the star of Bethlehem , what would the Bible provide ?

These pagan religions are not practiced anymore , and are referred as myth, so they’re not a threat.