This seems like a marketing move. When the Parental Advisory Label was created for the music industry, some bands and labels went out of their way to make sure they got it put on their albums, sometimes even altering their content just for that purpose, because it would actually drive sales. Of course every kid listening to rock and rap wanted "the real shit."
Here again we are being promised "the real shit" by a meaningless content warning.
It also helps Konami keep its distance from Kojima, which is probably what both of them want.