I see no support for his depictions.
And Murray’s books are about the best-supported books you could hope to find.
Murray is stating an important point, the person who wrote the review missed the larger point. The problems are cultural and values oriented not racial. Murray was castigated for writing The Bell Curve, yet the mess the ‘non white’ underclass is facing is the same as the emerging white underclass is facing. It will show itself in the form of lower IQ going forward but the issue is debasing the culture no race per se, and is ultimately the outcome of the socialist policies in the Industrialized world put in place over the past 90 years (in the US since the reign of FDR).
Not sure we can turn things around short of a complete collapse of the current structure and something akin to the great reawakening of the 19th century.