Walking around with a photo versus walking around with a hundred million photos and asking everyone simultaneously should not be considered about the basic same thing.
Like, is a victim of life threatening domestic violence who shoots their abuser during an attack a "murderer"? Or is an abuser who killed their spouse in a rage a "murderer"? Obviously these are different and the prosecution/defense hash that out over a very, very long time.
Details matter. Ask any public defender.
Note that we're talking about murder because the comment that set this off tried to pass off "throwing spears" as benign comparatively. No it isn't!
The spectrum stuff is about the likelihood of harm was my interpretation. Obviously we shouldn't be throwing spears, but there's probabilistic side of it that doesn't exist with nukes, and there's a spectrum between all of that with various probabilities of extents of harm. So if the harms of using these technologies intrinsically carries similar probabilistic risks (false arrests, elevated charges, etc), why not treat it as a risky object worthy of kicking someone off the range? I'm reminded of situations of waiting for the rangemaster to walk away so you can do something stupid and risky.
It's the same question though; how many right will we be asked to give up in order to catch rock-throwing assailants.
I lean pretty heavily on privacy not being a right in the direct sense or the penumbral sense. That a company sells a product that uses facial identification is to me not super relevant. If they had shown the photo around the department, and to random people at the university, and someone said "I recognize that guy, he's so-and-so" then there would simply be no problem here. Similarly if someone was just browsing through old yearbook photos and recognized the face. The computer system allows this to happen at larger scale, but the same basic thing.