Yes, this is taken from the paper:

"Given the inherent complexity of obtaining physical samples (except for mobile fauna caught in baited traps) future studies could use environmental DNA (eDNA) techniques on water and sediment samples to identify taxa", https://www.frontiersin.org/articles/10.3389/fmars.2021.6420... (Open Access)

I think you're right: too difficult to reach.

> ...after sinking a borehole through nearly a kilometre of the Filchner-Ronne ice shelf on the south-eastern Weddell Sea to obtain a sediment core from the seabed.

But you've already done the difficult part - you've drilled the hole, and brought samples back. Now you just need to bring back different samples. (And, I suppose, find a way to grab the right things...)