Here is the study cited. There are four health markers that were chosen to be analyzed for this analysis. Actual physical fitness (ie VO2 max, strength, body fat percentage) were not measured. In all but one of the examined studies, diet was not controlled for, and they specifically only included endurance exercise, when virtually every recommendation is to combine endurance and strength exercise. Claiming that this population doesn't respond to exercise is a vast overstatement. More accurately, you might be able to say that "Endurance exercise alone isn't sufficient to improve health markers in a small fraction of the population."

EDIT: The inverse to that is "Endurance exercise alone is sufficient to improve health markers in most of the population," which doesn't strike me as a good reason to not prescribe it.