It is not the client's job to protect the therapist. If she doesn't wear a mask and if the client is vaccinated - I would not worry about it. I would not see one if I was not vaccinated and didn't know if they had been. She gets to be an idiot (if she is not wearing a mask and is in person -then the assumption I would make is that she is not considering herself vulnerable) if she wants and it is not the client's job to protect a therapist from anything let alone their own stupidity. If I needed support from a therapisty sort- I would use an online service until the other live person was assigned.
If you really want to piss her off, get a hazmat suit. I would do that.