The Simple Life is a reality show with Paris Hilton. Not a tween/teen show. A reality show. And if that is the example they give, then I'll bet a month's salary the other shows were similar to (or are on) primetime CW/FOX shows. Tween/teen shows (Nick, Disney, etc) will have more than 30% teen viewership. The industry already voluntarily restricts advertising to shows with more than a 30% underage viewership. Adn don't be fooled by the "cable" misnomer. The Simple Life is a FOX show, not a cable network show, so they were reviewing broadcast shows as well.
Face reality, a study put on and funded by the UCLA Children's Studies is, by its very nature, prejudicial against anything that might be viewed as harmful to children and they will do averything they to make it look bad.
The alcohol industry doesn't advertise on High School Musical, but they do on 90210 and Gossip Girl and all these shows both teens and 20 somethings watch. That doesn't mean they are targetting the teens. It means they are targetting the viewers who can actually buy the stuff, the 21-34 demographic that makes up most of their sales.
So, no, I can't judge with certainty the study. But common sense and working in the marketing and advertising industry tells me all I need to know to make an educated conclusion.