What, you mean it's not obvious to you what a 14-year-old child should read with parental supervision? Doesn't everyone know that PG stands for Parental Guidance, and don't we all agree on what kind of content that is?
Riiight.
We don't agree on it *here*; I certainly don't expect people on other continents to understand whatever combination of morals & prejudices created the MPAA's ratings for movies, much less how fanfic authors apply those to fic.