You’re not crazy, all those risks exist. Right now, we are weighing the good of getting this content off the internet versus the theoretical bad our own system being misused.
How do you verify that the image being uploaded is indeed the user? Otherwise anyone can upload a photo of anyone else to see if they find something, which means you’d be taking the damage of revenge porn to a whole new level by creating an easily searchable index.
I don't wonder. The -only- way to really try to protect that data is to not share or make it available - even to companies that allegedly have good intentions.