I took that to mean that since her advisor told her that her committee was unlikely to read her dissertation before the defense, she took comfort in believing Dr. Mao - a member of the committee but a separate person from her advisor - would also not read it.

She does seem to state that her defense was conducted by three people - Dr. Mao, Dr. Hortense (who she did "go to" and got an unhelpful response), and "The third person in the room, another professor on my committee" who appeared surprised by the proceedings.

I think it's a mix of lawyer advice and a disavowal of Dr. Mao as her advisor -- a way to maintain some dignity. The member of the dissertation committee who is most likely to be "impossible" to remove is the chair. More evidence for the roles: "I told Dr. Hortense in this November email that I was worried about my ability to pass my defense, especially if Dr. Mao was not going to read it prior to sending it out to the entire committee."

The other half of the double-whammy is there are a lot of humanities degrees with no marketplace value beyond "has a degree" unless you have a PhD, so anybody in the position to impede your doctorate has more power than he would in a STEM field.