In all honesty, that wasn't necessary. The General Duty Clause could be used as a vaccine mandate because of the way it is worded.

This move by OSHA is just dotting 'i' and crossing 't' to make sure the Occupational Safety and Health Review Commission finds in favor of OSHA every single time this matter comes up when proposed citations are levied by inspectors against businesses.

By explicitly making a 'rule', this squashes most avenues companies and employees have to fight. Department of Labor (home of OSHA) is just as corrupt as any other governmental agency.