If Republicans want to abolish the EPA, all they have to do is pass a law. They could do it with a simple majority in each House if they abolish the filibuster (which itself requires only a simple majority).
There is no meaningful loss of democratic control here. Congress can do whatever it wants, with or without the EPA.
This is just the highest court in the land acting as toadies for the fossil fuel industry, legislating from the bench on a flimsy right wing legal theory.