Yeah. Got to be careful with that and how 'ANY' money is involved.
It's what caught out Nostralius when Blizzard sued over money being involved...
Azrael.
Yep basically it is "no money, no foul"
Ncsoft may try on general principal to shut this down but given that the code is already disseminated like the seed was at the end of sword art online one, they just need to sit back, grit their teeth, and realize they really screwed up with the shut down.
Now...if any private servers install graphics like billboards or graffiti that say "ncsoft sux" or something like that....then they might have a minor case in terms of slander but I am skeptical of that. Still, best not to hit the beehive too much