Seems like iOS 8 should offer a settings screen to allow you to revoke sync keys and/or see a list of computers you've trusted in the past. Perhaps it should default to deleting the keys if you haven't sync'd with a specific computer in some timeout period (30 days?).
A few of the services should be locked down a bit further regardless of anything else.
I also don't see this as a valid bypass of encrypted files - you need the device to be on and have its passcode entered. That's a far cry from taking a cold device, booting it, then connecting with a stolen sync key. Besides the fact that we've known you were unsafe if the device was unlocked for some time - some police even carry Faraday bags and portable chargers to keep them accessible probably for this very reason.
A few of the services should be locked down a bit further regardless of anything else.
I also don't see this as a valid bypass of encrypted files - you need the device to be on and have its passcode entered. That's a far cry from taking a cold device, booting it, then connecting with a stolen sync key. Besides the fact that we've known you were unsafe if the device was unlocked for some time - some police even carry Faraday bags and portable chargers to keep them accessible probably for this very reason.