TL;DR: They mine the Antarctic for ice, creating huge sinkholes, then fill the holes in with raw sewage, a gift for future generations. Environmentally friendly, right!
In contrast, the ice shelf is huge and still has a lot of capacity to contain sewage. It should remain frozen for the foreseeable future - if it melts (to the level where this sewage will become liquid) it means the global warming situation is so bad that there's likely no longer any humans around to actually witness this sudden deluge of sewage.
As long as we manage to keep that ice shelf frozen, we're fine. If we somehow fail at it it's likely there wouldn't be anyone around to complain about the sewage anyway.
Aside from that what do you think our ancestors did with their waste?
People overestimate the impact of individuals on the planet. Which is a game corporations play so you underestimate the impact of their profits on the planet.
"Tens of millions of gallons" of human waste sounds significant, but, it likely isn't. I also feel that equating the unavoidable byproduct of human scientific research in remote locations with road side burger wrappers is bordering on luddite hyperbole.
Although considering the desire to survive on the Moon and Mars, one would think recycling sewage in more of a closed system would be worth funding.
https://www.nsf.gov/geo/opp/documents/SPSMP_Fed%20Reg%20Draf...