Good chance you're right. But having SCOTUS come out and blast the mandate right from the top is a message that will really resonate in the country, and that cannot be evaded.
I think you are correct in your reading. This mandate is so far over the top and so far outside the scope of the authority delegated to OSHA and far outside the bounds of any normal ETS.
ETS are disfavored anyway. Off the top of my head, I think only 1 has been successfully implemented over a challenge.
This was such a crude and pathetic way to try an end run around delegated powers, that it is hard to believe that anyone would take the bait.
But there are a lot of “elite” lawyers that are fully on board with the idea of totalitarian mandates, and they will twist the law and the Constitution to achieve the ends that they want.