The irony is that they are deceiving themselves (if they genuinely believe this stuff, and it's not just a narrative to justify discrimination and morally repugnant behaviour). With these people there is a consistent pattern of flawed logic, poor study design, and what can only be described as magical thinking. For example, the correlation between illness severity and whether the person is member of a support group for people with this disease can be interpreted in different ways. They do not make an effort to find out which interpretation is correct. They also ignore the obvious explanation, ie. that sicker people have greater need for support groups.
Another thing is that they are seemingly unable to design a study that properly controls for patient and researcher bias. Without this, the results can either mean what they conclude, or it could just document the placebo effect in action, or describe the researchers biases. In other areas of medicine it has long been accepted that bias must be controlled or the results will probably be misleading. Without controling for biass, it's just pseudoscience. It looks a lot like science but misses a crucial element.
The recent study on emotional suppression did not demonstrate that patients with CFS actually suppress emotions. It is not clear what the results mean since the observer was an unblinded researcher. I'm absolutely certain that will not stop them from acting as if they (sort of, at least a bit) demonstrated emotional suppression and build on this narrative, coming up with more studies and eventually testing treatments. And they will always find a way to pretend that they have something real.