According to what I've read about investigations of online child abuse rings, to get into the members only areas, you have to provide CP to the board to be invited. This is sort of like a secret test of character such as doing a line of cocaine to prove you're not a cop to gain admittance to a drug dealing gang.Unfortunately it'll be back up in no time under a new domain.
Also in case anyone doesn't know Rapey has it's own Telegram chat group where its members are also located. I think now you have to be a registered member and obtain what is known as the "Rapey Badge" in order to access the invite link along with the hidden boards. I'm believing its no doubt as equally Horrifying as the site's content.
I suspect that might be how you get the Rapey Badge.
EDIT: It could of course be worse. The prosecution of online child sex blackmailer Matthew Falder revealed that to get into the "Director's Lounge," the secret inner boards of some dark web hurtcore site, you had to generate and provide original content.