Edit: Can someone confirm or deny the following? I think this is the current state of affairs. A) Apple will unlock PIN-locked devices by government request, but the best they can do is brute-force. This is very slow, as it can only be done using the phone's on-board crypto hardware (which has a unique burned-in crypto key), and the PIN is stretched with PBKDF2. It has been this way for a while. Apple has no "backdoo…
It's actually really easy to recover the passcode from iTunes backups (so probably from iCloud backups too). I've had to do it before to rescue photos off a friend's iPhone. Don't know about >iOS6 though.
Your example is a little unique though because you have physical access to both their computer and their phone. In theory you could just brute force their iTunes backup password.