While Kavanaugh could not be part of the decision to uphold his own earlier ruling for obvious reasons, the rest of the justices did him a clear favor by their decision. The optics of one of his egregiously dumb decisions being overturned on his very first day in court would have been awful. You can’t tell me the court isn’t politicized.
His earlier ruling was based on some flawed reasoning. Congress does not directly oversee each and every aspect of every agency. They (Congress) allocates the money, gives broad outlines to institute the agency’s mandate, and then would only step in if the agency ran far afield of that mandate. The EPA’s reason for existence is to protect the environment (it is the freaking name of the agency, for God’s sake), and it was doing its job with HFCs. When the EPA does NOT protect the environment, which has happened more and more frequently over the last decade as it is infected with Monsanto and Koch Brothers lobbyists, is when Congress should, but does not, step in; because Congress, like Kavanaugh, are a bunch of corporate stooges.
It is his shitty positions like this one that the Democrats should have been harping on during the nomination process. They chose not to. One may speculate as to why.