alt Hacker NewsIt worked well for the Terminator, so why shouldn't it work for us too? Being able to identify target/foe is of course how this will be used.
However, I'd be much more inclined for the Black Mirror use of being able to block someone literally not just a number in your phone.
I have some vague recollection of a sketch where the user walks around and gets popups and ads in his glasses and later removes them to discover there is a calm city life around him. Was that Black Mirror?