Villains may have targeted the Planet before, but now they have even more motive because they would know the place and the people in it are even more precious to Superman. Toyman and Prankster, for example, specifically targeted the Planet and its staff in Moore's Whatever Happened to the Man of Tomorrow? because they knew Clark Kent was Superman. In other words, the truth gives villains more reason to target the Planet and people like Lana Lang.
It's not splitting hairs. You're the one trying to fit a round peg into a square hole. Lois did not reveal anyone's civilian identity, and she certainly didn't reveal that Clark Kent was Superman. There is zero precedent for Lois Lane revealing the civilian identity of a superhero or the civilian identity of her best friend.Splitting hairs. She did reveal a secret identity. Masked Superman was a secret identity of Billy/Shazam.