If that is the point people are trying to make I am not going to relitigate Massachusetts v. Environmental Protection Agency and explain how it has nothing to do with Paris. I just do not care enough about this discussion to argue.
Massachusetts v. EPA and Paris have nothing to do with each other. Literally nothing. If the Environmental Protection Agency has a duty to regulation greenhouse gases for it is a public health risk, and the EPA official recognizes it is a public health risk, and congress in the various 1960s statues and amendments to those statues says it is in the EPA's power and not just power but it is their responsibility to act, because it is a public health risk that has nothing whatsoever to do with Paris. It is the various 1960s statues and the 1970s amendments that have the legal force, Congress passed it via both houses, the President signed it. This is what has the legal power.
Paris is peripheral and has nothing to do with the Congress vs the Executive battle of what the laws Congress past in the past and what the current head of the EPA believes his obligations are under these laws, and the president who gets to effectively control the head of the EPA (for the most part) via being the head of the executive branch.
It does not change anything.