25 Women in 10 Free Software Organizations for GNOME's Outreach Program for Women

Not necessarily.... you can have a a conference located in an area where your target audience is reachable and/or convenient to access, you can adjust the hours and date to be convenient for your target audience...
but that does not means that you have to do a conference that ban people that are not your target audience from participating...

iow 'outreach' program to a group does not necessarily imply discrimination against another group... like _this_ program does.

If someone is concerned that GSOC, for instance, is sexist and favor men candidate, then make the selection process double-blind, so that candidate are evaluated based on gender blind data, to make sure that no student get selected based on anything that the merit of his/her/its application.

"These exclusions don't sound to me like they should exclude any particular groups of people, but it seems like they do ---"

Indeed, the data indicate that theses and probably others do. But that is a symptom not the cause... Glossing over the symptom by paying some people to participate, based on gender to make the numbers 'look' better is not going to address the causes.

" and in the context of such a limited population, the size differences between sub-populations is much more than "marginal".

But this is assuming that these limitations (that 'prevent' the 99% from participating) would be easier to lift if you concentrate on one particular sub-group.... that seems hard to substantiate when the underlying factor are not quantified, and, for lack of data, it stand to reason that all the good reasons you gave that may prevent someone from participating, as you also aptly noted, should be gender neutral on face value.. and if they are not then _that_ is something that may worth addressing... but these would be societal/cultural problem that certainly won't be solved by introducing 'job discrimination' in a field that is culturally already much more inclined than the general population to value merit over irrelevant criteria like gender, creed, size etc...