What privilege? Her not being an asshole privilege?

I think they referring to the "privilege" of the attractive and popular. While I acknowledge that traditionally attractive people do enjoy privilege, this person is forgetting that the reason Snape was not well-liked (and the reason Lily stopped being his friend) was that he started hanging out with jerks, using bigoted slurs, and studying creepy dark magic.

If there's one overarching theme I notice in a lot of these Snape fanatics, it's a distrust for anyone popular or well-liked.

(Also, I think the "as a girl" thing meant "when she was younger", not "because all girls have friends". But I could be wrong.)