As a female engineer at WSU I am VERY aware of the lack of women in our field. Having an already somewhat small department, there is only a handful of women who are active in clubs. Even if they could get those women to help with the auction, it wouldn't attract the same attention that having a sorority participate has. We do not have a chapter of Alpha Omega Epsilon at WSU (Yes, I know that it is an engineering sorority. I am a member of AOE from a previous institution). We also do not have any chapters of the several engineering fraternities.
Knowing a majority of the guys in the auction and organizing it, I don't think they are being sexist or ignoring the fact that women can be in technical majors. While it may not be the best way to encourage women towards CS or Linux, I don't see anything particularly disturbing with the event.