What they are doing is putting pressure on the fed government to mandate, they have not.
The Feds do not issue State health mandates.
So if the employer is not in one of those categories then the FWA advice for them is to seek expert legal advice. Which effectively distills the compliance argument down to following "lawful and reasonable instruction" from the employer, throw in privacy protection laws preventing employers from checking if their employees are actually telling the truth and it just becomes a bigger mess.
I think the OH&S laws override the FWA in most States.