"Wow, even the kids in the seventies probably didn't know what Dinah was talking about. They're public domain!"
It was a common enough reference that the kind of kid who read comic books would have known what it meant, even if he wasn't familiar with them first hand.
At least, when this came out, I didn't think "What the hell is she talking about?"
Oddly enough, that reference seemed less dated then than the "Raymond J. Johnson Jr." one that the Star Spangled Kid makes seems now.