I'm not so sure about that. The wording in the contract under the 30-Day Cancellation Period I think you're referring to states:
"Also, you may have to return any handsets and accessories purchased with this Agreement."
First, there's no statement that you must return the equipment. Second, unless activations are being done at the time of equipment purchase, the service agreement purchase is a separate transaction from the equipment. Third, my receipt from the Apple store makes no mention of a requirement to activate service. I say this because as a DirecTV subscriber for years, I'm all too familiar with their sales agreement that comes with every receiver sold. Basically, when you buy a new DirecTV receiver from standard retail channels, you acknowledge that you will activate service on that receiver within a certain period of time. If not, you give DirecTV the right to charge your CC for a certain amount of money (I think it's like $200 or something like that). Again, that is done at the time of purchase. Nothing like that was done when I bought it from the Apple store. So, I see a variety of ways that a customer could avoid being forced to return the equipment.
Also, forcing equipment returns within 30 days would be a processing nightmare. Why? Because the hardware return policy on the equipment is only 14 days. What the heck is an Apple store supposed to do with a customer who cancels after 3 weeks and is told by AT&T that they have to return the equipment? Seemingly they have to return it to the point of purchase. If AT&T didn't make the equipment sale, AT&T taking it back directly would make for a revenue problem. Obviously, the 14 day return policy is a contract policy instituted by Apple. They want their money for the hardware. I have a hard time seeing them instituting the policy but then working out some way of accommodating 15 to 30 day service cancellations.
I highly doubt that anyone would be forced to return hardware post cancellation.
Jeff