The court cites it as an overreach of the Executive, not of the Federal Government as a whole. They imply that if Congress issued a law, they would follow it. Or if you were Barrett, then if the States implemented it, then SCOTUS wont challenge it. Thankfully, the Senate issued a vote prior, condemning the OSHA mandate along party lines. This made it unambiguous where Congress was at regarding any mandate.

Bottom line is that they seem to favour it if Congress or the States did the mandate, especially if it was the States that did it.