Why doesn't the MPAA want kids to see "Bully"?

Bullying has existed in different forms for centuries, but the prevalence of such incidences manifesting themselves in new ways over social networking sites and driving kids to suicide in our modern day is what is so alarming. Indeed, recently there have been various meaningful victories for equal rights in America such as gays being able to serve openly in the military. We've even seen celebrities take part in spreading awareness of the seriousness of homophobic hate crimes and bullying in schools while providing an optimistic message for the victims and encouraging them to look to the future.
So in light of how bullying has taken so many different forms, why would the MPAA give the new documentary, "Bully", an R rating?
I understand there will be some violence in there and there will probably be some coarse language used too. But my argument is this: kids in middle school and high school see this every day. Why, when this information could be used for positive change, are we limiting the audience that will be able to view this film?
The idea that the kids over 13 but under 17 will somehow be negatively affected by watching this film, is absolutely ludicrous. At risk of sounding redundant I repeat, the media within this film is nothing short of an exact portrayal of what they already see and deal with every single day at school. The only difference is that in the real world they're watching it without the guidance or commentary of their parents!
I'll be honest, part of my issue with the MPAA's decision to give the doc an R rating is due in part to the fact that they are a completely secretive and privately run organization lacking any reasonable transparency. The very board of individuals who rate these movies remain protected by anonymity.

None of it makes any sense, and after giving it some thought, I realized there's probably an ulterior motive behind this decision to give "Bully" its R rating. Perhaps, those running the MPAA and all their rich buddies, don't want to spread this message of tolerance too widely. Why, you ask? Because if the kids were to become more tolerant of their differences they'd realize the truth about many of America's most influential figures; that they're just a bunch of bullies. Those kids would then become tomorrow's voters, and a tolerant and compassionate generation would never support the radical conservative agenda that seems to be the strong undercurrent driving our policies today. Instances like Republican representative Virgil Peck saying we should shoot immigrants like feral hogs, or when commentator Ann Coulter coldly joked about gay stereotypes saying if she had a gay son she would ask for help redecorating the dining room after telling him he was adopted, would never fly with a compassionate audience let alone have their vote. Would they then not have a much harder time selling their conservative elitist agenda to an informed generation of voters who act on compassion and acceptance of diversity?
I say all this, slightly kidding. I don't really know what the MPAA has to gain from a conservative agenda, even though they've been known to show favoritism to major studios over independent films among other inconsistencies... But the idea's not that far-fetched.
Here's a clip from the documentary, "This Film is Not Yet Rated" which goes into the secretive and unjust nature of the MPAA, and the way that they dictate who should watch what movies.

If you agree that "Bully" will do more GOOD than harm with a PG-13 rating, sign this petition.
The children, who are the victims in all of this, are waiting for society to change their attitude on the issue of bullying, to take it seriously. But how will that ever happen when the first work that could actually provide a basis for that dialogue is rated R?

Now you be the judge. This is the trailer for "Bully", being only a few minutes long there is not a whole lot to go by, but clearly a central point of director Lee Hirsch is that the problem of bullying is often ignored and left unaddressed by teachers and fellow students, who are an essential component in turning this problem around. Hopefully enough people will sign the petition to put the necessary pressure on the MPAA to assign the film a PG-13 rating. Otherwise, a very large part of the target audience may not see this film until they are old enough and by then they'll be graduating from high school.