No, that hasn't been proven. If you look at the Fluge and Mella study that you're referncing for this, you'll see that the scatter graphs overlap, so the evidence isn't terribly convincing. Also, the downregulation of the pyruvate link step that they found is consistent with increase glucocorticoid receptor activity (the stress system).

>Talk therapy is no longer recommended

That's a pretty skewed review you posted. All the evidence points to CBT being effective for CFS. Certainly it can hurt patients when applied improperly, such as forcing patients to ignore exacerbation of symptoms. But that doesn't mean it is all bad.