What federal mandate to wear a mask?
Section 1 of the Executive Order, says:
"Accordingly, to protect the Federal workforce and individuals interacting with the Federal workforce, and to ensure the continuity of Government services and activities, on-duty or on-site Federal employees, on-site Federal contractors, and other individuals in Federal buildings and on Federal lands should all wear masks, maintain physical distance, and adhere to other public health measures, as provided in CDC guidelines."
Notice it says SHOULD ALL WEAR MASKS, which is not a mandate, it's a suggestion. It tells me it is still my choice to wear a mask and you can't enforce a SHOULD. And to previous posts note it is the "CDC Guidelines". Guidelines are suggestions not law.