About BlackBerry Messenger
With BlackBerry Messenger (BBM), you can chat and share in real-time with your BlackBerry contacts. For example, you can see when someone has read your message and when the person is typing a reply.
I suggest that you research the difference between text messaging (SMS) and IM (e.g. BlackBerry Messenger) before making pronouncements like that. There is no suggestion in the AAIB report that IM was being used, nor any reason why it should have been.
I'm sure that the AAIB will have the 'authority' to get whatever information is needed to interrogate the different pings and pongs and timelines from the various networks and devices.
Of course they do. But you have yet to demonstrate that there would be any record of an SMS that was being composed (hypothetically), but had not yet been sent, at the time of the collision, other than on the phone itself, and there is no reference in the AAIB report to the device having survived the impact and/or the post-crash fire.