I hate to be that guy, but seriously? I have never witnessed this kind of behavior before. In fact, from my experience at Cal, all of the student groups are absolutely desperate for anyone to join, let alone a girl! If you just walk across campus you will be aggressively flagged down and invited to all sorts of things. If you are on Facebook, you will be shamelessly spammed with invites to all sorts of events. I just can't picture someone getting shunned from even an IEEE meeting or hardcore hackathon because they are "not a true geek".
I'd like to think adults are more mature than kindergarten-level exclusion, fellow hackers most of all.
She then goes on to say that she bought vintage gaming t-shirts and worked on some video games and afterwards, all the geeks were "cool" with her again. I don't really know what I'm trying to say here other than this seems totally unbelievable.