It reinforces the stereotype that only women are mean. I would dislike a title reinforcing stereotypes about me: "Detox for Alcoholic East Europeans: Haskell type enforcement".
I don't know the movie, so I agree with the title being a bit strange, and I probably could have done with a slightly more factually oriented article, but I appreciate the effort to keep it light. And the stereotypical girls' cliques the article seems to riff on do exist... Girls are known to be more relationally aggressive than boys, who tend to be more physically aggressive than girls. Girls also behave in a more pro-social fashion, so girls' cliques are often larger than boys' cliques, creating more complicated power dynamics. That said, I don't really get what you mean. That's like saying a book called "Good Habits for Incompetent Managers" reinforces the stereotype that only managers are incompetent.
They are referencing the old idea that men handle disagreement with violence while women handle it by being mean to each other. Saying "only women at mean" is hyperbolic, but they likely are stereotypes.
For what it's worth, I've never considered meanness to be limited to non-physical attacks. I'd venture to say a bully punching a kid is just as likely to get labeled mean as a bully that makes fun of a kid.