Re: What about that 'Cellbrite' kit?
Yes, if they are truthful in saying they've exhausted all other avenues then I guess that means Apple has fixed the exploits Cellebrite used the last time (which was on a now seven year old iPhone/iOS)
I think the FBI may be wanting to remove all the past objections, especially the egg on their face when they insisted they had to have Apple's help then got a third party to unlock it for them (and found nothing of value on the phone) so they're trying to cover all their bases this time so Apple may really be their last resort.
Obviously they're hoping for a sympathetic congress (won't someone think of the murdered servicemen's children!) to pass laws banning this type of encryption where no one holds the key except the end user. And damn the unintended consequences where every other country does the same and the phones belonging congressmen stolen by a "pickpocket" when they are overseas are trivially unlocked and all their secrets exposed to China, Russia, Iran etc.