As a counterpoint, sure shut down your copy of it if you feel sufficiently threatened... But give away the 'fully baked' software ready to host, and somebody in a completely different jurisdiction could stand up a new copy of it.

Good luck to newspaper owners suing somebody who lives in a small town in Balochistan who finds a way to buy a .IS domain name with cryptocurrency and pay for KVM VM hosting in Moldova. Or somebody similar who has the financial resources to go host the thing in the same physical location/ISP where archive.is has server resources.