Err, when people think "Fake Geek Girl" aren't they more imagining the ilk of Jessica Chobot and TradeChat? You know, the people who post pics of them sensuously licking a nintendo DS or in a bikini for views and fanservice while claiming they're super nerds? Basically, people making money off the gaming industry while knowing next to nothing about it.
I've never seen a girl in artists alley with a batman T-shirt get the 3rd degree from some neckbeard. People claim it happens "all the time", but I have female friends, some very attractive, who have been going to conventions for like 12 years or more and they've never run into this fabled inquisition. Also, they cosplay. I'm not saying it doesn't happen, but I can't imagine it's a plague that runs anywhere but the internet.
One of the same friends is a really hardcore gamer. I've never met someone who has insisted, to the point of contention, that females can't play games. Colour me perhaps a little bit skeptical at how widespread this witch hunt is.