The included illustrations also show that his art was anything but photorealistic. Perhaps the use of that term was just meant as a little joke. (He's a realist painter, and he uses photos. Photo realist!) I'm not sure. Anyway, the idea that Rockwell was a proto-photorealist is, I think, deeply misguided.
The blurb is a mere soundbite, but it manages to get at least one, and perhaps two things wrong. In this particular case, they're just minor slips--misleading, but no doubt not recognized by the author as being anything worth thinking too carefully about. I don't want to be too hard on the blurb.
I mention it only because it fits so well into the pattern of Rockwell criticism that just gets Rockwell wrong, largely because the criticism is so thoughtless, and fed by vague associations rather than careful study.