Because this post was uploaded in July 2016, 6 years before the G rating was implemented which was in May 2022; topic #29394
They weren't referring to the rating. The post was tagged sexually suggestive.
As for why, my best guess is that someone stupidly assumed the hand gesture was related to a penetration gesture even though she's clearly making a 10 with her fingers.
Chief, what the hell is this? Why bother peeling off these labels from bananas? For the balance of the universe. Sorry, I just remembered this moment, then he just stuck a label on his forehead