I didn't see the talk but I have had problems with what the Lights have said before on this. They seem convinced that nothing abnormal happens in the muscle but our body thinks there is for some reason. But abnormalities of various kinds have been found.
During the panel discussion, Dr. Klimas asked Alan Light about the practicality of using his exercise tests to guide treatment. While Dr. Light suggested that his test had potential to guide treatment, he was concerned about asking CFS patients to excessive because of the damage it does. In addition, he stated that one of the keys was to determine how much exercise would illicit a detectable and detectable response while at the same time minimizing harm to the patient.
I was very much under the impression that Dr. Light is well aware of real damage and not just issues in pain signaling. His comments did not seem to support a conclusion that he feels nothing harmful is happening.