As a man I have found the linux community extremely toxic, RTFM etc, over time this has gotten better, but I would hardly call it sexism.
fwiw the Kernelnewbies list and irc is another good place to start for civil kernel discussion. I would suggest that common to both it and Linuxchix is the belief that no matter what the questioner or respondents' level of expertise, the only possible response to a question is a positive, helpful one.
Also, I would rephrase the "geek machismo" to "geek hardassery" since machismo seems to outline masculine pride. I do, however, agree that people tend to be hardasses with the whole RTFD/RTFM angle and that's something we could collectively improve upon.
Conversely this sort of behavior when dealing with vendors where money changes hands is almost non existent. And I suspect this is because there is a economic incentive in place for people to act civil to each other.
Complaining about this dynamic wont change it only changes to the economic model will change peoples behavior.