Sondheim did get into the "goss" (is that slang for gossip?) about why she wanted the lyric changed.
From page 155 of Finishing the Hat:
"She [Dorothy] recognized the marriage I was writing about as having characteristics similar to their own (not the homosexuality alluded to—both Rodgerses were dedicated homophobes, despite Dick's closeness to his homosexual partner Lorenz Hart)."
