Yep, when I connect to the VPN and then look at the last IP of my user account in Discourse it shows the IP that my VPN gave me. However, when I open an incognito browser window and try to register a new account then it doesn’t allow it:
New registrations are not allowed from your IP address.
So it appears that “Screened IPs” are just for registration, not for completely disallowing access to the website.