Which means the phone stores a copy of your fingerprint so it can make the comparison, right? If so, then someone could steal the phone and get that information. Doing that in a Faraday cage blocks the ability to do a remote lock and wipe.
The bottom line is that hackers will look for opportunities to exploit, and they have a history of finding ones that make vendors facepalm and say, "Why didn't we think of that?"
if a crook has already broken the back window, he doesn't need the front door key. Which is to say, if the hackers can break into the device and access the data without using the biometrics, the biometric data is no longer needed. In that regard, today's complex pass codes would be equally pointless.
The real concern is whether there's a back window that can be broken, not the quality of the front door lock. If such a back window exists in iOS, I think we'd know about it by now, on the dawn of iOS 7, and I seriously doubt agencies like the Defense Department would be certifying iOS devices for use.
And if the point of the break-in was to obtain the biometric data? I can't imagine many of us have fingerprints that will be more valuable than the other stuff we keep on our iPhones. In any kind of rational system, actual biometric data is not going to be stored or used in the banking system, specifically because fingerprints are pretty easy to steal (the old detective-grabs-the-water-glass scenario), and can be changed just a maximum of 10 times (different finger). The biometrics are isolated within the device, to validate that the device is in the right hands. That will be in addition to, not in replacement of, the account numbers, PINs, and passwords we currently need to use banking apps. If a device becomes untrustworthy (reported stolen), the bank simply stops accepting transactions from that device. Pretty much the same way it works today with lost/stolen credit cards.
Finally, using a Faraday cage to bypass the remote wipe capabilities in iOS 6? That'll soon be trumped by the anti-theft capabilities of iOS 7, which, apparently, have made those attorneys general very quiet.
