The nurses were given training in the BPS view of MECFS, and it sounds like they truly believed they had the "truth". They simply couldn't fathom why the patients were so critical of this view. In an article Tuller quotes about the trial process, one or the trial supervisors said “Their frustration has reached the point where they sort of boiled over,"... “There is sort of feeling that the patient should be grateful and follow your advice, and in actual fact, what happens is the patient is quite resistant and there is this thing like you know, ‘The bastards don’t want to get better.’” .
I think it's an interesting facet of the whole CBT/GET approach to ME/CFS that the therapists/nurses/listeners, whatever, are actually more brainwashed than the patients. The reason for this is simply that patients can tell first hand that it's not making them better, nothing to gain from kidding themselves, whereas the practitioners have to either accept the treatment they are responsible for, and that they have vested interests in, doesn't work - which involves believing someone else and accepting the lack of evidence againsy what is being told you. Accepting you are wrong, failing, is hard. Much easier to shift the blame onto the patient.