I agree that's it's very pseudo-scientific. But then human relationships will always be incredibly pseudo-scientific, because science is all about systems of causality and it's incredibly difficult to predict the behaviour of other human beings.
I think there is no definitive guide to flirting; the best way to get better at it is to just work on your courage and self-control and then practise, practise, practise. Still a lot of the things in this article seemed to match with my own personal experience so it gave it a bit of credibility in my eyes.
BTW, I am in no way a PUA of any sorts. I mean, I haven't been to a party in two months and I haven't had a girlfriend in just over eight. Still I found it interesting, in a kind of "ooo" way.