Well, apparently, that was the conclusion of their study or studies. If he had confidence in what the studies showed, how else should he have responded?
For my part, I began reducing volume significantly about 3.5 years ago when I first came across these studies, having been prompted by the predecessor to this thread on ET. I only very recently settled on 1 set per exercise, and even that was short-lived, despite my recent assurances that I was going to stick with it for a time. My compromise is one set to failure followed by about 10 to 20 seconds rest and then a few more reps to failure again. So it's not quite 2 full sets, but it's more than one. I take a 2- or 3-minute break between different exercises. Twice a week. With any luck I'll stick with this volume for a time...
I do this sometimes and sometimes I do more when I am not in a 'lazy cycle'. Trying to maintain at this stage, zero interest in being as big as I was back in the day but definitely want to maintain existing muscle mass and keep the natural testosterone pumping now that I have just clicked 40.
Recently, I posted the results of a study that showed a single set to failure being superior to a forced rep set to Repetition Maximum. Not quite an apples to apples comparison, so it would have been nice if both groups had done either Repetition Maximum or to Momentary Muscle Failure. Better yet, it would have been more informative if the study had RM and MMF groups for both a single set and a forced set. Maybe next time...