The study has been widely slammed by patients and researchers. It was badly run, far too small and finds nothing novel not already found in better bigger studies while trying to shoehorn more psychology nonsense at patients. It would have been useful in 2017 but we are in the COVID world now with extensive Long Covid ME research which has found more insights into the disease.
The big problem is the introduction of effort preferences and no real study of the key unique symptoms of Post exertion malaise. The study points to no underlying mechanism so gets us no closer it's just a collection of wrong things proving people are ill, but we have known that for decades.