What we know:
It's all due to legal issues with Activision. The website and NP Server were shutdown due to advice by NTA's lawyer. It now seems the website has been brought back up and pointed to these forums.
Here is what NTA said on the IRC channel (a day ago): https://i.imgur.com/vBHOFKF.png20.0K
(Lovely is NTA's IRC nickname).
And.. this is why the service was suddenly brought offline:
(blummy) lovely, did you shut it down on demand or just at your own will
(lovely) blummy, recommendation from my lawyer
fourDeltaOne's COD projects were great whilst they lasted... RIP.