In this case it doesn't. If there is a catastrophic failure on earth so big that it wipes out all electrical systems and kills all computers the ISS won't survive for long without any resupplying. In that case you'll have an ETH node orbiting earth in a station full of dead people.

Such scenarios are mostly hypothetical, and would mostly include world-ending situations such as planetary impactors.

Do note that I'm not advocating for ETH-nodes in space, I'm just putting up reasons for sending [stuff] into space. If you had a very lucrative webshop, you could decide to do HA by sending some of your servers to space. It doesn't logistically or practically make any sense, but the reasons for doing so are not wrong per se.