According most flat earthers, there’s no such thing as the continent of Antarctica. In their imagination, Antarctica is not a continent, but a long ice wall enclosing the Earth. Without having anything to prove that assumption, they look anywhere for any quote they can mine and stumbled into this quote by Admiral Byrd:
“Strangely enough, there is left in the world today, an area as big as the United States, that’s never been seen by a human being. And that’s beyond the pole, on the other side of the south pole from Little America.”