I am sorry what is it about ice being melted by volcanoes escaped your notice ?
You mean the section that says "It is important to note that none of this research suggests that global warming and climate change are not affecting the ice sheets of Antarctica but they do imply that any melting due to global warming is being exacerbated by geothermal heating from beneath the ice cap"? Yes, I read that. I also read that "A survey of the thickness of the Earth's crust in Antarctica found a particularly thin zone under Marie Byrd Land, where the Thwaites Glacier is located, which is consistent with the presence of a 'major volcanic dome'", which indicates that this is a long-term effect and should not affect the net rate of melting - it would be part of the steady state if we had one.
Despite that the coverage area is still increasing
Again, what is increasing is the maximum sea ice extend. The ice mass balance is strictly negative - i.e. there is more ice melting than water freezing year over year. The amount of ice is going down, by about 70 Gt per year (albeit with large uncertainties), and accelerating.