Not getting on the subject of purity rings as I shared this for a laugh, not to bang my head against the wall and/or nitpick & quibble.
This ep actually slams Disney more than anything. Even the JoBros (Jonas Brothers) got off with a light roasting. The short & sweet is that Disney is much more concerned with showing "moral" entertainment than Nick (though it's amazing how much crap the writers manage to get past the censors before Disney catches it and clamps down on it). Nick is Nickelodeon, btw, Disney's biggest rival on TV. (DreamWorks gets mentioned by Mickey as their rival in the ep, but they'd actually been taken over by Disney a few months before this aired.) So many parents like it, including Christian families (though some of the more extreme fundies reject it as promoting witchcraft and rife with subliminals) who consider it more wholesome. But kids being kids, especially with money and adoring fans in places like Hollywood, tend to get a bit wild and this upsets the parents who fear their kids will imitate them (and also many girls, especially tweens, are really vigilant against "sluts" to the point that wearing a bikini while lying on a bed or touching a pole for more than 5 seconds will get them reaching for the metaphoric pitchforks). Miley, while well meaning, is an attention whore with a trollish sense of humor (though don't get me wrong, I do like her) and I can only imagine how many times Disney has wanted to strangle her for riling up both tween fans and a great many parents (though some moms & tweens are such hypocrites and/or plagued by double standards, like when a bunch condemned 17-year-old Miley for wearing a tight shirt "selling sex" while also getting wet for 17-year-old Taylor Lautner taking off his shirt in one of the Twilight movies at the same time). This gets especially distressing to parents when its BOYS who their tween girls are screaming over (sometimes even going to the concerts without vigilant adult supervision), especially when they're in a band (and everyone knows what debauched freaks they are). So in order to placate parental fears and even expand their audience base Disney had the JoBros wear "purity rings" which promised puritan-like behavior and thus could be trusted AND even serve as role models, if the boys they love promote such values then they'll also pursue boys (so parents believe) who also claim to hold similar values. In short, giving purity rings to the JoBros (and later others, including girls) made it possible for Disney to sell sex (at least infatuation, think of it as like porn/erotica for tweens, but in disguise) to good Christian daughters.
And it's not just the customers, but it helped soothe the fears of parents of their precious stars (which would cost Disney millions if parents pulled them from production). Like when Selena Gomez (who, IIRC, debuted for Disney in one of the Spy Kids movies and then became a character on Hannah Montana--which the JoBros also guest starred in, btw--before getting her own place of honor in Wizards of Waverly Place) joined Disney she was given a purity ring which made her conservative Christian mother feel better who had been frightened that Hollywood would corrupt her innocent daughter, but since Disney got her to wear it then Disney would obviously safeguard her moral character (right?). But then Selena, who was getting closer and closer with the Bieb, ended up taking it off...and her parents flipped out, or so it was said by the gossip mags (but by then she was 18).
So that's what is meant when Mickey says in the ep that he can do anything he wants, including in selling sex to young girls, as long as he makes sure the JoBros wear purity rings, because people are fooled way too easily.
Btw, when someone in the South Park ep explained the purity ring meant they weren't to have sex until married one character did ask, "Isn't that a wedding ring?"
"Never underestimate the power of sex, which has built and obliterated families, nations, and food co-ops." --Dyke Drama, by Leslie Lange
"Life in Lubbock, Texas, taught me two things: One is that God loves you and you're going to burn in hell. The other is that sex is the most awful, filthy thing on earth and you should save it for someone you love." ~Butch Hancock
"A penis was not meant to go into a man's butt, but rather a womens." --excerpt from an illiterate rant to a gay rights page
"if you consider the fact that cats and dogs are of the same species you would still find it odd if a cat acted like a dog now wouldn't you" --from the same rant as above