Protecting Kids or Just plain stupid
I don't think they're idiots, I think they have a valid point.
PG-13, according to the MPAA, means that some material may be innappropriate for children under 13. Burger King's kids-meals are intended for children 4-9. They have a point that it's innappropriate to market a movie to kids that are below the age the movie is intended for.
That being said...does it really require all the grandstanding and "OMG protect the kids!" No, if you don't like it then don't take your kids to Burger King. It's not like we're talking about "Hot Interracial/Trans-sexual Gangbang Lust" move-inspired Happy Meals...."look mommy, my prize is a soggy balloon...what's this white stuff?"