You certainly didn't refute what I said. You are quibbling about qualifications. I'm sure some people are denied entry to the United States. And others are denied entry to Russia. Access is controlled by the Antarctic Treaty

Ask the tourist companies where they can reach. They seem to be a bit coy about that. But the fact of the matter is that the Antarctic ice cap is perhaps the most hostile place on the face of the Earth, and the prohibitions are meant to preclude the loss of life. Did you even read the material at the link? There are expeditions to the interior, at least to the South Pole or Mt. Vinson.

Look, you can carp, or you can scrape up the kale and go there. No travel anywhere is for free or without restrictions. The trail to the peak of Mt. Everest is littered with the corpses of tourists.