Unless you can point to a breach of some specific contractual term in the Eula there is no cause if action. The suit is nonsense.
Why does someone need to show a breach with the EULA? The issue concerns the advertised capacity of the device. When the iPhone is purchased, it states in the documentation that the capacity might be less due to formatting of the device, not because of subsequent forced downloads that have nothing to do with the formatting. Furthermore, no where in the iOS 6 license/terms of use, does Apple reserve the right to reduce the capacity of the device beyond what is necessary to format the drive. Did you even read the EULA?
The EULA for iOS 6 says that Apple "may make future iOS software updates available". Great, make them available to me, but that does not imply that I consent to having those updates pre-downloaded. So if the update actually consumes 3gbs of storage space (and this isn't formatting related), then Apple is reducing my storage capacity by 3gbs. Apple is guilty of false advertising.
I'm pretty sure there are consumer protections laws against someone selling me a device with capacity X GBs and subsequently making only X-3 GBs available.