Ah, but remember that in this example everyone sees the posting (or, if you prefer, the recruiter only reaches out to women who see the posting) so your scenario is impossible. The recruiter's role isn't to increase visibility but rather to be a signal to women that they wouldn't be wasting their time with this company.
When programs like the one briefly mentioned in the article are done well their net effect is really signalling more than anything. As trivial as it sounds, such signalling can actually have a large impact.
Both of the students are CS majors. They presumably will both eventually work for similar companies. Why would the woman who is equally interested in computer science pass over the job posting, requiring an actual recruiter to be present, when the man does not? Do women get CS degrees and then leave to work in some other field post-graduation, not writing code? If so, that is a huge problem. Do they lose interest in computer science? Do they get sick of the male dominated environment in CS but just stick it out for their degree?
I would hope that the recruiter isn't, in fact, signalling something along the lines of, "your odds of getting hired at this company are greater than your equally talented male friend." If I were receiving that much extra recruiting attention because of my gender, that is the impression I would get.
I hope you don't mind if I'm not interested in spending a few hours tracking down all the sources I've referenced before but to give you a short answer to your first paragraph: for the past decade or so women have held 20-30% of the CS degrees with recent times being somewhat higher. Women also hold less than 20% of the software positions (http://www.pbs.org/newshour/rundown/2012/04/science-engineer... ctrl-F for "19 percent"; it cites the Bureau of Labor Statistics but I'm not sure what part). Obviously there's not a perfect correlation between degrees and jobs for a number of obvious reasons but it's evidence against equal chance of CS majors staying jobs. And I've seen separate sources more clearly showing that there is larger fall-off for women than men. Unfortunately, I don't know what the cause is exactly.
However, your second paragraph sort of has things backwards. The current scheme of things strongly signals to women (pretty accurately) "your odds of getting hired are lesser than your equally talented male friend." Such signalling as I described before isn't about saying that their odds are better than their male friend but rather that the company is actively trying to not disadvantage women.
The current scheme of things strongly signals to women (pretty accurately) "your odds of getting hired are lesser than your equally talented male friend."
Do you have some sort of evidence for this? Anecdotally, talented female programmers stay on the market far shorter than males do. Most companies desire a gender balance, which makes the limited stock of female programmers more vlauable.
When programs like the one briefly mentioned in the article are done well their net effect is really signalling more than anything. As trivial as it sounds, such signalling can actually have a large impact.