The article relies heavily on a Dr. Kellman from an eponymous clinic in New York City. Never heard of him. Does he have any bona fides in the field?
I've never heard of him either but this would seem to be him, https://kellmancenter.com/team/raphael-kellman/
An abnormal response to exercise is not mentioned. In 2020 we should expect and demand that anyone claiming to be an expert, spokesperson or researcher into ME should know that. It is the defining characteristic of ME. The horrendous consequences of the arrogance of Stephen Strauss and the corruption of the CDC are still condemning us after all these years.
Reading from his site I think Kellman equates cfs with hypothyroidism. So not particularly well informed.