Ask HN: Why can thepiratebay's URLs be used for redirecting but not hosting?

The torrent-hosting site thepiratebay is constantly changing TLDs. Right now it's thepiratebay10.org, but its previous URL at thepiratebay.rocks still redirects to the new one.

How can it be that the .rocks url needed to be moved on from, but can still be used for forwarding? I don't understand how the game works. I would have thought that if it had been seized, they wouldn't be able to use it at all. And if it hadn't been seized, why move on and forward to another one?