I agree with this, AND I also believe T's have the right and obligation to say something if they are uncomfortable. One way that a client can learn about boundaries is by watching T set boundaries in a healthy way.

If the rest of the session was about T being scared, why she was scared, how to manage her fear, etc. it would be completely inappropriate. But to say "it scares me to learn that you spent time looking up the genealogy of my family" is just an honest response that informs Rainbow of how her actions may affect others.