Of all of the discussion, my brain has only keyed in on the child porn aspect. It just now clicked that if a missing kid is in a photo (even if not porn), it could help ID the missing kid. Some runaway at the age of 13 gets photographed in a group of other kids just doing teenager things.

So even if not running hashes against known porn, it could still be doing facial recognition. Wonder what kind of implications that would have for people in witness protection or battered spouses and other legitimately "disappeared" people.