Hogwash. Pure conjecture—just so you know how I “feel” about this issue. People need a job, and writing anything that appears authoritative will work to keep them employed. A worthless piece of “research.”
Your post? Yes, I agree, hogwash and pure conjecture.
You’re reacting to the deliberate insertion of politically correct language, “culturally diverse.” However, the fact of the matter is that there are different styles and possibly methods of tool-making evident in the artifacts, so there were different populations. It’s unfortunate that the temptation to retrofit modern notions of diversity was too great for the author to resist, as it debases all that was written. There were obviously diverse cultures present though, despite the freighted meaning.