I assume that "liquid cooling loop" has an endpoint outside of the building which hosts hardware. In this case it's exactly same problem - just make pipes longer.
Do you need many acres of land to host a heat exchanger?
So how much does the bunker help if you can just drone the cooling systems on the surface? The the computers either cook themselves or have to do an emergency shutdown.
If the other end of the cooling loop is a giant reservoir, as is the case with plenty of other 100+ mile water transport systems, it doesn’t matter if you drone it. Fly all the drones you want into Lake Anthropic, there’s many more cubic meters of water than there are drones.