Can you make an ethical argument against it? What ethical principle is violated by photographing people in public? By classifying those photographs?
"I would not want my photograph being surrepticiously collected and used by an entity/organization for an indefinite period of time, stored in an indeterminate number of locations, and with unknown goals that may be related to mass surveillance; therefore, I will not perform that same action against others"
And based on others HN comments, even if it's not the majority opinion, it is not an exceptional opinion.
I wouldn't be surprised if that were the case.
"In the United States, a right to privacy has not ever been used by courts to restrict photography of people in public places. Not even once."