Miley Cyrus is not a 'tween. 'Tweens are the not-quite teens that marketers "discovered" in the '90's. Miley Cyrus is a teen. She's marketed to 'tweens, but she isn't one herself.
Here's another thing that Miley Cyrus is not: the first average kid/rock star character in a sitcom that has weird parallels to real life.
Ms. O'Roarke is only in her early thirties, so she may not remember The Partridge Family. I loved that show. Every week, I tuned in to watch that dreamy Keith Partridge, the regular-high-school-kid-rock-star. He was played by a real rock star, David Cassidy. David Cassidy was nothing like the product packages as Keith Partridge. His mom on the show was played by his real step-mom, Shirley Jones.
Of course, even David Cassidy wasn't the first kid on a sitcom who was a musician in both real life and on the show. Ricky Nelson and Desi Arnez Jr. also come to mind. (And their folks on their TV shows were also really their parents.)
So, what's the difference with Miley/Hannah? Is it because she's a girl? There might be something to the gender difference. Too bad the article didn't focus on that difference.
Instead, the article assumes that Disney is giving us something new, and that today's 'tweens have an interest in celebrity that previous generations did not. With just a little research, there might have been an interesting article.