IMHO, no more ASB than the Inuits IOTL.
Well, not in the sense of requiring magic.
The point is, the Inuit cultures are the historical climax of a very long succession of Arctic and sub-Arctic cultures that adapted to extreme enviroment gradually as humans came from other populated areas. This because the Arctic is connected to other populated areas quite extensively. Critically, it is
ecologically connected, meaning that a trickle of ecological diversity from the big landmasses gets there and has a chance to adapt. This means that Arctic areas have a fairly large variety of plants and both marine and land animals humans can live off.
OTOH, the unfrozen bits of Antarctica have a grand total of 4 species of vascular plants, one of which might (or might not) be marginally edible. There are no land animals to speak of. Essentially, no ecology that could feed humans, except from the sea. And Antarctic seas tend to freeze for obnoxiously long periods of the year and irritatingly large expanses of space. You have simply no local natural resources to build a trophic chain over, unless you import them. Importing them is difficult for the very reason they aren't there in the first place, namely that there is nowhere in the neighborhood to get there from. You have not enough ecological room to replenish local ecosystems with anything that isn't ice, or sea life. Hell, almost nothing that create
soils or keep them there once created. So, a Inuit-like little group that accidentally ends in Antarctica has relatively dim chances unless they're bringing a self-susatining piece of ecology with them. This means having an extreme variety of Arctic "agriculture". DValdron's done an exceptional job at devising one, but IOTL it didn't happen, and probably there are strong reasons why the Inuit and other Arctic cultures didn't develop anything of the sort IRL. Let's say you have this package; it is developed in the Arctic. To get it into Antarctica, there's the whole planet in the way. That's why I suggest to take LoRaG's boosted Maori. They are very good sailors, and New Zealand is sort of closer to Patagonia than Alaska. In a LoRaG like scenario, they might be needing other places to go, and Patagonia is better than most in that at least very few are going to challenge them about
that area. But still, we are assuming a lot of stuff that didn't happen IOTL.
Then, you have Maori people having colonized the southernmost tip of South America. You'd need them to get a suitably sub-Arctic crop package, let's say they get it with contacts from the Thule by sea (it's just sailing along the entire American continents to get to them somewhere around Alaska, after all). Then they'd need to have the population pressure that pushes them to island-hop into even more inhospitable places such as Falklands, South Georgia etc. until they stumble onto Palmer's Land, and when they do so, they'need to be desperate enough to decide to settle those most godforsaken barrens. Finally you'd need their settlement to survive in a very, very extreme environment to which they have only limited pre-adaptation (with relatively little gradual transition to new environment) where they have to build an ecology from scratch.
That's tall order.