Yes, politics forums tend to be more male than female, but not all politics forums are as male as this one. There was another thread on this years ago that I can't find now, and I think it was Beet who made a good point there about how the Atlas forum is unusually isolated in cyberspace, and not tied to any particular personality or blog or whatever. It's just something that you stumble across if you're looking for election results. The hypothesis was that it being so isolated might result in the demographics here being different than they would be on another politics forum.
OK, but why would the isolation, in turn, make the forum more male.
Well, Wikipedia isn't isolated from cyberspace (among the top-ten visited websites), but about 85% of writers are men. Women use the internet to connect with people and men tend to write or discuss about specific issues they are interested in (politics, science, architecture etc.).
My wife's Facebook page is all about kids, grandkids, family, etc. Mine is all about religion and politics, with some sports.