I will say that if the therapist or a close family member (like someone they live with) is particularly high-risk for a medical reason (like immunocompromised, getting cancer treatment, organ recipient, etc.), then I could definitely see them wanting to remain virtual and would entirely understand. And while I don't think they owe a full explanation of why, to at least say something to the effect of "for personal safety/health reasons, I need to stay virtual."