I feel the same. I first heard of Neil Harrison as a speaker at the
IiME Research Conference in 2015, enjoyed his presentation on the conference DVD, was pleased to know of his interest and involvement in ME research and have no doubts about his sincerity and good intentions.
I also don't object to researchers trying to prove or disprove their functional neurological disorders hypothesis in ME or CFS, provided that selection criteria are clear and methodology above board etc., but the phrasing in the overview of the study that you linked to concerns me.
"We have previously developed a theory that we believe provides a reasonable mechanism for how symptoms are produced. We have already gathered evidence that supports this theory in patients who have functional symptoms affecting movement (e.g. weakness, tremor) and sensation (e.g. numbness). We now want to move forward and test if this theory can also account for symptoms experienced by people with chronic fatigue syndrome and non-epileptic attack disorder." http://gtr.rcuk.ac.uk/projects?ref=MR/M02363X/1
I also noticed that at end of the second of these two interesting interviews kindly given by Neil Harrison in 2016, he mentions the work of a researcher in Australia, Andrew Lloyd, whose research activities look impressive to me, but then ends with this:
"He has recently completed the Cancer Australia-funded Treatment of Post-cancer fatigue Study (TOPS) trial, which demonstrated the effectiveness of cognitive-behavioural therapy and graded exercise therapy in the management of post-cancer fatigue. In the UNSW Fatigue Clinic he leads a multi-disciplinary research team conducting both pathophysiological research to better understand disease menchanims in medicallyt-unexplained fatigue states, and also clinical research to improve existing cognitive-behavioural therapoy (CBT) and graded exericse therapy (GET) treatment interventions." http://gtr.rcuk.ac.uk/projects?ref=MR/M02363X/1
As I said, I find Neil Harrison personable and interesting to listen to, and do not doubt his good intentions, I just think it makes sense to be alert to the possible disadvatageous outcomes of well-meaning biomedical research activities until we have better tools for differential diagnosis of ME.