Gating content in such a way would have no effect on the games rating. The rating would still ramp up if said content was in the game (Wether minors could use it or not)

It's like saying Grand Theft Auto could be E for everyone if you didn't break the law, beat up hookers, or shoot everyone in sight. It's totally possible to obey trafic laws, be a taxi driver, or even live a honest life!