Is it so difficult?
"We recognize that everyone's personal circumstances are different. Don't hesitate to continue wearing a face mask if you feel more comfortable doing so. Also, please respect every individual's decision to wear a mask or not,"
Well, the masks are primarily there to protect others. This still hasn't sunk in?
So if someone is especially vulnerable, then that person should be able to insist others meeting her/him should wear masks.
The easiest way to implement this is that if you are meeting someone who wears a mask, you put yours on as normal curtesy.
But that would just be too simple and logical, wouldn't it?
(Of course, normal politeness seems a very strange concept to many people. Not only do they not put a mask on when they see others using masks. They instead try to invade other peoples' privacy and make them take theirs off. Especially in USA this seems to be a thing.)