Jesus, they have to realise its not about whether its a superhero movie or not that gets it a rating, its about what the subject matter is.
Whats next, a Freddy Kruger film with a PG13 rating? A Saw film with a PG13 rating?
When you look it certain superhero/comic book adaptations, some should certainly be PG13 (GL and Wonder Woman etc) and other should be more adult (Punisher, Wolverine & Ghost Rider etc), purely based on what the character is like originally!