The industrial ancient DNA publication machine is real. A few giants control the vast majority of ancient DNA samples behind a wall, and these giants decide when and where to release these samples. I was part of a study, that got mashed together with a totally unrelated study at the last minute, for the sake of another hyped headline in Nature/Science, which reviewed and accepted the article very quickly. The whole process felt sloppy & rushed, and I was left with a bitter taste that ultimately led me to move on to other areas.
On the other hand, I have immense scientific respect for David. In population genetics, there are a whole host of methods used to infer demographic history that are very biased and ignore important forces like natural selection. David's group has pioneered statistical methods that are more robust and less biased, that make less sweeping claims but are on much sounder scientific footing, and used these methods to derive important insights on human history.