I'm inclined to agree with you that he got a lot of the details wrong, but nonetheless I think he's pretty much on-target with the logical conclusion of the endeavor.

The impact on society has been at the level of something rather less intricate than even the Cliff Notes version of postmodern thought, and in part because of that I think it does bear a large degree of responsibility for weakening the injunction to understand things clearly, favoring instead perspective and narrative.

Which in turn favors those who can sculpt perspective and narrative.

In a tremendously complicated world where actions do have consequences even if you can't always easily discern them, Horkheimer's old injunction to form dynamic unity with the oppressed class contains the key to all manner of regressive social and intellectual trends. Why? Because it places goal above understanding. Humans do goal easily; understanding is hard. When given a chance to be lazy and feel great about it, chances are we'll take it, even if we repeatedly do the wrong things for the wrong reasons because we haven't internalized how difficult it is to achieve any goal if we don't know what is and is not the case.