How could he have successfully executed this fabrication? Doesn't he work with entire teams of others, don't others review his work, his analysis, the data collection, etc.? The idea that one man, alone, could pull off such a large deception seems, to me, to be pretty farfetched.
Some additional context here is that in academia, there has been a lot of pushback on the burgeoning field of behavioral economics as a result of political viewpoints; nudge is inherently a liberal concept, and puts conservative viewpoints of personal responsibility in a negative light.
Combine that with the ever-present reproducibility problem in all of psychology, and the economists who were made to look like fools (in their view) in the earlier years of the 21st century are striking back with exactly these kinds of arguments (economics isn't strictly a "hard science" insofar as it can't really run experiments the way physics can, so it's easy for economists to point out experimental issues).
Ariely's books aren't "BS", and throwing that in there kind of shows your hand. Large portions of his books are explanations of the work of others, and even if everything this UCLA professor says is true, that doesn't invalidate a single thing he wrote about in his books, other than perhaps specific citations of his own work (of which we're talking about a tiny handful of hundreds of published and peer reviewed studies he worked on with thousands of other people).