There is no indication that Argentina is accepting the Chinese offer, but I can understand both why the Chinese are making the offer and why it would be attractive to Argentina.
The current Antarctic treaty is set to expire in 2048. It seems unlikely it will be renewed. Too many want to exploit mineral wealth that is believed to be there. There are already known conflicting claims on the continent, including overlapping claims by Argentina, Chile, and the UK. Even Japan has stated an intention to make a claim.
Neither the US nor China has made a claim yet, but they are likely to. The US has a strong basis for claims, and China has been investing heavily in Antarctic exploration and research.
Argentina has few friends likely to support their claim. Relations with the UK and the US have never fully recovered since the Falklands War. Relations with Chile have always been strained. Argentina’s military is now much weaker relative to the UK than it was at the time of the Falklands War, but they still claim the Falkland (Malvinas) and South Georgia, both of which are under UK administration. Argentina might want to have China on their side.