The article isn't really about saying literally that all MNers have children called Felix and Tallulah, etc. It's more about suggesting that there's a fair amount of leftie groupthink about on MN, and that in a lot of cases that comes with a dose of hypocrisy as the MNers competing for who can be the most right-on are on the whole pretty middle-class.
I have to say, I think I can count the MNers who I've seen admit they voted Tory on the fingers of one hand.
Personally, I loathe the Guardian, think Toby Young's free school sounds like an excellent idea (I couldn't give a toss if he's an arse or not, though it sounds like he quite possibly is) and voted Tory because I couldn't stand the idea of another four years of paranoid, over-regulated market Stalinism. So shoot me.