The phone could nag you mercilessly about any disturbing pictures on your phone, without notifying any outside authorities. That would accomplish 50-75% of their goals.
I thought their strategy is similar to Valve's anti-cheat - Tell the offenders absolutely nothing up until you snap shut on them.
The consequences between cheating in pub Counter-Strike are obviously less serious, but Valve does let people cheat for a while and then bin people into "ban waves" (last I heard, anyway) to try to throw off the trail and prevent cheaters from figuring out exactly which actions got them in trouble. It's also similar to the concept of hellbanning trolls from a forum. They won't comply with kind messaging, they'll just instantly shed their accounts. So don't let them know they're banned.
There is a whole (even more fraught) conversation about how to get pedophiles in touch with psychiatrists before they commit any crimes, but telling them "pst, I'm onto you" peacefully probably isn't the way.
