As is often noted in Antarctic colonisation threads, the key problem with Antarctic colonisation isn't just food, but other resources too. Animal skins will only take you so far when there's not enough useful plants to supplement a human diet and most importantly making technology common to most hunter-gatherers. Antarctica is far worse than the High Arctic in terms of it's human habitation potential thanks to this lack of plants.If I decided that Antarctica would be colonized,it would be the Fuegians primarily due to the fact that they are already adapted to the cold. Moriori would be later if then. But much like their Arctic counterparts, the Antarcticans would have a primarily meat based diet with similar ways to cook leopard seals,penguins,whales and whatever Antarctic fish is around. And they might be more seafaring if for nothing else than how inhospitable mainland Antarctica is.
The Fuegians would do far better since they'd island hop down a landscape that gets more and more like Antarctica the further south they get. The Moriori or pretty anyone else would fail on arrival to Antarctica since they'd be island hopping across a much greater distance from much more pleasant (relatively, it's still basically Iceland-tier) islands to a far more desolate part of Antarctica. That's where ASB would need to come in.