"Any ownership interest by Mr. Goodwin in [the copies of his data that remain on Carpathia's servers] would be limited by at least two separate agreements: (1) the contract between Carpathia and Megaupload regarding Megaupload's use of Carpathia's servers; and, more specifically, (2) the written agreement between Megaupload and Mr. Goodwin regarding use of Megaupload's service."
The government's argument isn't about inherent ownership in copies, but the impact of relevant contracts to the ownership interest. The line of argument isn't good news (and hasn't been adjudicated) but it is cause for cloud storage providers and users to closely examine how their contractual arrangements address the issue of whose property the cloud-stored copies are.
On a paper submitted by a physicist colleague: "This isn't right. This isn't even wrong." -- Wolfgang Pauli