> a) it introduces private healthcare decisions, a legally fraught topic they do not want to deal with. Is it legal to fire someone for refusing to return to the office despite health concerns? Probably, but no one knows for sure and your employer does not want to be the test case. (If they ask, "what health concerns?" remind them that's private. Don't invent a fictitious medically-fragile aunt.)

I used to be a lawyer (though was never a labor/employment lawyer) and am having a hard time coming up with reasons it would be illegal to fire someone who refuses to come into the office for unspecified medical reasons.

It seems like you've thought about this quite a bit — what would the reasoning be? Employees have lots of protections, some of them related to medical conditions. For example, employees can get access to FML under the appropriate circumstances. But my understanding (having claimed such benefits for my family when babies were born) is that some sort of proof is required to establish eligibility.

Are there other benefits or protections that would not require this? Or is there a 'protected class' designation that could be claimed? For the record, I have no dog in this fight — I work for myself and don't have employees, so this doesn't affect me personally. I'm just curious what the arguments are for employees who want to remain remote.