It's sociology, what do you expect? ;-) (I nearly majored in sociology in college, taking 4 courses before I switched first back to physics and then to computer science. This gave me both a basic fluency in the lingo and a healthy disrespect for its conclusions or lack thereof.)
Anyway, you have to understand the particular school of thought she's coming from. This article's steeped in the lingo of Gramsci and Spivak, who studied primarily power relations within society, particularly the question of "Who decides who can speak?" In sociology, there's the concept of a discourse, which is basically "What can you talk about without getting odd looks?" Certain discourses are legitimated: you can talk about Heroes or Desperate Housewives or Paris Hilton or the Red Sox and everyone will find it socially acceptable. Certain discourses are relegated to specialized niches, but still socially acceptable: you can talk about monads or CSS or DNA replication and people won't think you weird, but they may not listen either. And certain discourses are fringe: if you talk about how 9/11 was an inside job or put on eyeshadow and leather pants for a goth party, people will think you a little nutty, unless you're on Reddit.
In this context, the article's list makes a little more sense. What's considered socially acceptable discussion in high school? Pop music, the latest movies, that party at the class bitch's house, homecoming, cheerleading and school spirit, and apparently Facebook. What's not? Having to work to support your family and put yourself through school. Slacking off and doing lots of drugs. Weird art bands that nobody has heard of. Local music that nobody has heard of. Wearing odd clothing or odd makeup. Being gay, unless you live on the northern portion of either coast. And apparently MySpace.
Basically - ask yourself "Who would you want your daughter to date?" Unless you're one of those enlightened parents that believes in letting their kids make their own choices, you probably wouldn't want her going out with an art fag. You wouldn't want her dating a stoner or a gansta. You'd look at her a little weird if she brought home a goth or a punk.
This is different from the notion of social class that William Julius Wilson or Barbara Ehrenreich writes about. That's much more (though not wholly) economic and educational, and is closer to popular definitions of social class. The Gramscian notions of hegemon/subaltern are much more about power and people's unconscious reactions to cultural behavior.