I mean, a unique digital fingerprint can be created by the links that your device makes with other devices without you having any input at all
I think the point here with the patent is the number of photos that the user takes with other users... then you enter in the circle of verified people, this is difficult to cheat by a bot/IA I think (at least today 2019).
Then, in this sense they can introduce "one account one vote" in Voice without taking into account the stake.
Oh yeah, and what happnes when you lose your device? Not sure.
I suppose that you can recover your account with other device. Just take again more pictures of you and claim that you are the real one. As the old device can not create proofs (pictures of you) then the blockchain can update your device id.
It is already possible to know which devices are near to other devices. So if somebody steals your phone then that device will enter into connections not previously established and hence trigger some other protocol that the original user needs to perform. As you say, perhaps a new photo, although what about taking a photo of one of the selfies in the stolen phone?
The real owner could take a picture of himself showing in a paper the most recent hash in the blockchain. But yeah, this system becomes more and more complex. So it is difficult to be 100% and more difficult considering the advances in artificial intelligence that will come in the future.