But, on the other hand, his counterargument for the existence of other potential factors seems to me to be quite weak and lacking the same rigor. The existence of "basic sex differences" is not discussed in detail, with only a couple of references. And a lot of his counterargument seems to be based on a few example countries with high gender equality rankings and low STEM participation.
Is there any validation that these gender equality rankings are a useful indicator of gender equality? What about factors that surface only after school/college in these countries? What about network effects in various fields?
Not that I'm saying such factors do exist. But the author makes a somewhat strong (IMO) argument against stereotype threat, implicit bias etc. and a very weak argument for the existence of other factors.