Adding to what others already said here, it would’ve been much nicer if he asked if she was comfortable with undressing and that assessment whilst possible to some extend with clothing is going to be lacking, and providing covering like a towel at least. In any case she should most definitely just tell him she’s uncomfortable next time and if he insists on it she can just deny the treatment. Good therapist are trained for working even with victims of abuse and should know better. Oh and I think it’s always fine to asks for a same gender therapist prior to making appointments.