This question may not be able to be answered by people that aren't members of the MPAA or Sony.
No one but the MPAA (and possibly, but not definitely, the studio) knows the exact criteria the MPAA uses to rate films.
As pointed out in the documentary This Film Is Not Yet Rated, The MPAA will not reveal any information about who or why certain decisions are made, and that the association will not even reveal to the filmmaker the specific scenes that need to be cut in order to get alternative rating [ Kirby Dick (2006-01-25). This Film is not Yet Rated (Film)].
Edit:
Trey Parker and Matt Stone revealed that Major Studios can get information from the MPAA regarding the reasons specific cuts of films have received their rating, while independent movie producers can't get the same information. In the same interview they quote the MPAA as saying "we [the MPAA] caan't tell you what to cut because that would make us a censorship organization".
It might be fair to say that only the MPAA or an executive of the Sony would be able to provide the answer to your question. If Sony has this information, it may have been leaked during the Sony hack.