On the contrary I feel like he himself is at the peak of the dunning-kruger curve, and doing his best to bring lots of people up there with him. The "FR is everything" crowd is deluding themselves into not hearing extremely obvious differences and characteristics just because some supposed authority told them they don't exist, when said authority derived those conclusions from their own biased interpretation of the specific research and information they chose to read.
The reason we don't have "measurements" for things like detail yet is because they cannot be quantified into one graph or number, and many of those perceived effects are caused by multiple different specific measured behaviors, as well as being connected to each other in various ways. You can't just put that into one graph and rank different headphones by some "detail rating" in a table; it's something that needs to be explored on a case by case basis to determine how exactly the driver is behaving when given different types of signals and what audible effects that is causing. It's definitely not easy, but better than insisting that a single graph dictates everything that we hear and dismissing everything else as placebo.