The whole point is that the token itself doesn't have any personal info attached to it, only a yes/no and expiry time.

I'll even one up my original suggestion - it uses standard public/private key encryption, where the government issues a simple json token with a yes/no Boolean and a TTL. The public key that can decrypt the tokens is public. Pornhub then decrypts the token and verifies the boolean and expiry date, all without talking to the government at all.