I agree that it's useful to discuss the issue prior to and after. I doubt that there are very many patients that are not affected by a T's vacations, etc. Many patients are so affected, it takes up at least two of the sessions on either side of the absence, sometimes longer, as some need to feel "safe" again once the T is back. They need to be assured it's safe to trust.
I don't think Ts need to overstate what goes on when they go on vacation, illness or whatever. What happens is real. I believe it's because of the therapeutic relationship. Maybe the author doesn't develop, or acknowledge, this with her patients???

I don't know who she has in the mix: clinical psychologists, social workers, group counselors, self appointed advisors?
That therapist's are "taught" to expect the upset of the patients has no basis for the supposition of exaggeration of the fact, imo. There are countless events in therapy that are expected by the T, but that doesn't dictate giving in to poor therapy, does it? No, only with untrained counselors, imo.
It's always a good thing for a T's vacation to coincide with a level, calm, manageable period of time for the patient. I think the affect also depends upon how often a patient sees the T, and how much dependance has been fostered (for right or wrong reasons.)