That land glacier is a very, very small fraction of all of Antarctica’s 14 million sq kilometers.
Most of which is covered by land ice that is gaining mass.
If you want to have some fun with a global warmunist, ask them to figure out how long it will be before Cape Horn is closed to shipping by Antarctica’s expanding sea ice? (if current rates continue as they have since 1992, Cape Horn will be blocked in 8-12 years by sea ice.)