These are just from the first page.
The Constitution gives Congress the right to make laws that regulate interstate commerce (Article I, Section 8, Clause 3).
Congress used that power to pass the Occupational Safety and Health Act in 1970 (signed by a GOP President).
That act established OSHA, and gave it the power to enact emergency measures, which this is.
Follow the path; there is the Constitutionality of this mandate.
But ...
It has to pass the inevitable court challenges, which could be:
1. "It's not an emergency."
2. "It's an undue burden on industry."
3. Something else out of left field.
I think it will pass, but these days, I underestimate nothing.