Yes? He's admitting he doesn't have the expertise to address that. Evo-psych is definitely not a generally accepted scientific field, so I don't really take issue with his off hand dismissal.
As far as I understood the original manifesto was about the average population characteristics of currently existing men and women, so those studies shouldn't have anything to do with Evo-psych, I mean they would be valid even if evolution didn't exist.
There was a passing mention of evolutionary psychology in one of the points where the author was explaining other reasons for the gender disparity.