I don't think this is relevant for "genuine" CFS. There is a difference between Long-Covid and Post-Covid, and I'm sure we will find this difference for other virus, too.
AFAI found out until now there are people who suffer "just" from fatigue, including Post Exertion Malaise, Postural Orthostatic Tachycardia Syndrome and dozens of other symptoms, all of which are consistent with a secondary mitochondrial dysfunction and physiological coping mechanisms running wild aka CFS, Post-Covid, me.
And there are people additional suffering from chronic inflammation aka ME, Long-Covid, chronic EBV/CMS whatever virus.
For ME/Long-Covid this study is relevant for shure.
Just what is the relevance? I don't know at the moment.