There's no rumor. The article just states that Playboy desperately wants Miley and Selena to pose for the mag.
Which shows that not all of the current miserable state of Playboy is mismanagement. It's the current state of the world where men get naked even though no one wants to see it and women don't get naked, even though everyone wants to see it.
Yeah, people here take Playboy to task for not getting more celebs, but it's not as though they can just get anybody they want to pose.
It's more a North American thing than a world thing (I say North American instead of U.S. because you don't see known Canadian women doing it, either). The international versions of Playboy don't seem to have a problem getting celebs from whichever country they're in.
If it was really a case, as a lot of folks here imply, of there being tons of well known women wanting to get their kit off for Playboy if they'd just call them, then some other mag would have stepped in and filled the void.
The reality is that the well known women can get just as much publicity and promotion posing in a bikini or lingerie for Maxim and the like. Why get naked when they don't have to?