I wouldn't be too much concerned. The article is a lot less dismissive of PUA than what is usually put forward, even on this site. Plus, it's not that La Ruina isn't another little Mystery clone.

If a 17 year old boy picked at random can probably figure out how to close the deal with a girl for the first time

Based on what I know of my culture (US or other European countries might differ), not even 17 yo boys who do get girls know better. They usually get them because of a combination of some better looks, wider social circle, inferior opinions on women.
Those who apply for a PUA seminar are the ones who are trying to optimize their understanding of females, letting aside the fact that you cannot will yourself into being non-anxious. My opinion is that if they could be at ease around the opposite sex, they would wind up with a better sexual life than their "natural" peers.