Hard to say if we lost or won. Very difficult and confusing case. The Supreme Court thought about it for a while and decided to punt.
When given a really tough, highly politicized case, that is what the Supreme Court has generally done.
There have been exceptions. I think of the Dred Scott case where the Court "decided to decide" a case that was political and to "settle" the political issue.
That decision lead directly to the Civil War.
Such is our system, be it for good or bad. Maybe when AEP and TVA and the others have no choice but to shut down those coal-fired plants and people lose their jobs and freeze in the dark, there will be a run on the EPA.
Overreaching bureaucrats beware. It could happen to you and it won't be pretty.