I know its easier than ever to dunk on how terrible reddit has gotten, but honestly? What is this? How is is safer to deliver this content to kids viewing reddit on a tablet or PC or in the app? Why even create the bs excuse?
They could just have easily told the truth an displayed a message like "Content is limited. Open in the app to view." It's still a jerk move, but at a minimum its honest.
You can get iPad 10th Gen which is pretty good option for kids, I recently got one through free tablet wireless website and it's working really great..