Legal consequences of using photos of identifiable people are not limited by copyright[1]. For example, it is quite easy to assume that photos from this service will be used for political defamation, among other things.

How could they enforce it? For example, by embedding a steganographic tag, by which human rights activists will be able to identify the author of the picture.

[1] https://commons.wikimedia.org/wiki/Commons:Photographs_of_id...