That link argues that each individual interbreeding population does have psychological unity, but there are differences between populations.
I see an argument that different populations could have different means for certain quantifiable traits. I don't see an argument that a single population will be homogeneous.
Moreover, the link claims that populations have diverged on these metrics in fairly short amounts of time. I think that that is evidence for a fair amount of diversity within populations to serve as the raw material for that divergence.
So PUA techniques should work or fail depending on ethnicity. (Yeah! I win the Non-PC Award!) Is that what you believe?
I should clarify that I'm not convinced by the link's claim that populations differ on those metrics for genetic reasons. But I certainly allow that it's possible. It's not ruled out by what we know about biology. I presented the link only as evidence that the case for psychological unity is not a slam-dunk.
Followup to: Do you have High-Functioning Asperger's Syndrome?
LW reader Madbadger uses the metaphor of a GPU and a CPU in a desktop system to think about people with Asperger's Syndrome: general intelligence is like a CPU, being universal but only mediocre at any particular task, whereas the "social coprocessor" brainware in a Neurotypical brain is like a GPU: highly specialized but great at what it does. Neurotypical people are like computers with measly Pentium IV processors, but expensive Radeon HD 4890 GPUs. A High-functioning AS person is an Intel Core i7 Extreme Edition - with on-board graphics!
This analogy also covers the spectrum view of social/empathic abilities, you can think about having a weaker social coprocessor than average if you have some of the tendencies of AS but not others. You can even think of your score on the AQ Test as being like the Tom's Hardware Rating of your Coprocessor. (Lower numbers are better!).
If you lack that powerful social coprocessor, what can you do? Well, you'll have to run your social interactions "in software", i.e. explicitly reason through the complex human social game that most people play without ever really understanding. There are several tricks that a High-functioning AS person can use in this situation: