Women who are beautiful in a traditional, heteronormative way are objectified and given more praise/recognition in all walks of life, not just in geek culture (such as the fact that beautiful women are more likely to get jobs/promotions). But the essay is right in saying that geek women who are not considered "hot" are more open to ridicule by being referred to as "annoying, squeeing fangirls". What's even worse is that I have never seen that label applied to the "sexy cosplayers", but only to the geek girls who are either fans of attractive male characters, and/or who create actual content within fan communities (such as fanart and fanfiction) that are deemed socially unacceptable (such as slash/yaoi and mpreg).
One thing I disagreed with in regards to the essay is that sexy cosplay can be used to subvert society's expectations. The problem lies within the fact that it doesn't matter what someone's reasons are for wearing a sexy cosplay outfit, all the guys are going to think is, "Hey look! She's showing off her body!" So it renders the original intention behind the costume moot, unless that intent was to cater to men in the first place.