[digookdigook]

I wouldn't call it a bluff, but FUD. Of course the carriers can MITM pretty much all traffic, unless the keys were exchanged on a private channel. The internet is not private, SMS 2FA ain't either. It's FUD, because the spin that this announcement is a bluff would lead Terrorists from using it anyhow, revealing sensitive information. Putting on the tin-foil: If even I could figure that out, perhaps it's indeed intended as deterrent, e.g. because AI is not strong or efficient enough to process the amounts of data. That's still less paranoid than thinking AI was indeed strong enough and just keeping people busy with unsubstantial stories.

Of course there's also the theory, that even governments are sometimes just stupid.