I think you could argue teenagers have a right to discuss political issues in the public forum. That's basically the definition of good citizenship, and (for better or worse) social media is the public forum of the day. Kids don't go from zero rights at 17 to full rights at 18; minors' rights are limited, but they do have rights.

I dunno if that'd fly in Australian courts though.

Kids not being informed about the war crimes of their state, and other states.