I wonder what's their real agenda with these photos. You can never take what Facebook says at face value. Just like when they say they're only building shadow profiles on you for security purposes.
These friends will miss you. ... We might have to start serving them the images you uploaded instead, or they'll get lonely!
"We're terribly sorry this database of photos submitted to prevent revenge porn was accidentally made public. We have fixed the security hole which made this possible, but still intend to keep and expand the database which was exposed. Thank you for your understanding and participation."
Or, imagine a new advertising filter popping up some new advertisements for you: "Have genital warts? Use our cream to make them go away!"
I can see a new zuck quote now... 'i asked them for nudes and those idiots just gave them to me'
Facebook is in the middle of a PR disaster which sank their stock price because they gave away data to companies that users agreed to give away. Nude photos are probably more sensitive to people than their social security number and bank information -- especially to younger people.
The public outrage that would follow if anything nefarious was happening to voluntarily sent nude photos would be tantamount to destruction of the company. It's not hyperbole -- the whole point of submitting photos to stop revenge porn is to stop the spread of the photos. Anything else would contravene that trust and spark moral hostility.