So any idea when this will actually be an OSHA standard and subject to litigation?
No. News reports say is has been submitted to OMB for review. Once it is published, it could be published to take effect immediately - at which point it is ripe for litigation. How long will OMB take? Don;t know. Will there be a public comment period (typically 30 - 60 days), my guess is "no." This will be crammed down the throat of the public. It'll like have "reasonable accomodation" langauge for people who object on religious or medical grounds, but will expressly exclude natural immunity as a medical ground.
Once OMB concludes its review of the regulation, the emergency temporary standard will be published in the Federal Register, when it will go into effect.
If that news report (link) is correct, the regulation goes into effect immediatly on publication. OMB has no longer than 90 days. It went though this process with an OSHA rule that applies to health care workers. Went to OMB April 26, 2021, out of OMB June 10, 2021. Six to eight weeks.
Emergency temporary measure promulgated a year and a half later. What a sick and evil government we have.