If you consider the moral rather than the legal issue, it should be pointed out that there is a REASON for intellectual property law. Intellectual property uses the law of possessions to monetize something that is not traditional property for a purpose... to reward the creator of intellectual work for the act of enriching civilization.
I suggest that if you use IP law to PREVENT the dissemination of IP, you are completely reversing the purpose of the law. Your MORAL right exists so long as you are making the IP publicly available (under whatever terms). If someone is holding IP with no intention of using it further, then it has no MORAL basis to its ownership as it is rather PREVENTING the enrichment of civilization.
But this is moot, with the IP necessary for the game being in the freely distributed client (and as I understand it that was distributed with no express or implied agreement) -- then just as ICON uses that client, so could a server, and as long as that server did not use missions or stories from the original (beyond what is in the client), what rights to the game's IP could be violated?
If a Reverse Engineered game consisted of entirely new missions, AE built lore set up to be assigned by contacts rather than through AE, for example, how is it violating the game IP?
In that case you described it's probably not breaking the law that why I stated a couple of time "Depends on how it's done".
But in the case of COX IP, the company haven't stated either way if they are intending to use it for the future or not, it was just assumed by some that they are not even though they didn't say and probably wouldn't publically release a statement for us in that regards either. So right now, I don't think no one can factually say they have no plans for the IP and thus may not be preventing enrichment of civilization although I think it would be a stretch especially in the court of law trying to demonstrate how COX IP non-releasement is detrimental to the enrichment of civilization. But I get the point and they haven't said either way so whether or not they will use the IP is factually unknown outside NCSOFT.
LAw is usually written and defined with the meaning or definitions being argued. Morals vary person to person and thus sometimes morals and laws don't go hand in hand. It would be morally right for someone to donate a car they are not using. But legally, they cant be forced to donate the car whether or not they are using the vehicle or not regardless of how many neighbors are riding the bus.
See if one is not using their IP, which was designed so people could get rewarded for their work and get compensated, then they are not making money. Thus should they be forced to give it up? In this situation, many will say yes in a heart beat. But in law, you have to think about the bigger picture and just not NCSOFT. Everything from movies, some IP that haven't been marketed in decades but the holder of rights are sitting on it for what ever reason, to upstarts with a bright idea and new way of doing something that register their IP only to lose all their hard work to major corporations because they didn't have the fund to use it.
I guarantee ya, while in short sight it looks like being forced to give up rights that not in use, in this case only a year, looks like it will benefit the common people, in fact it will bring ruin and their ideas will be usurped in mass by major corporations that have the money to put on a token marketing to keep it without paying the creator of the IP a single penny. Thus nullifying the entire purpose of IP protection for anyone that don't have millions hanging about thus in the end corporations like NCSOFT will get even more powerful with IP hording. And more than likely they probably just bounce it around among their buddies to reset the clock each time which the common man probably don't have the cash to pull that without risking everything they worked on.
While there are downsides to the current way, I think ownership rights should not be taken away. If one manage to built a server without using trademarks, IP, copyright materials and etc, they have nothing to worry about and it will be great. But it would be foolish to think there is zero chance that nothing will happen if they steal the whole shebang. Something might not happen at all, but the risk is still there.
If Morals over ruled law, then there would be not a single homeless starving person inside this country while other have billions while getting away with paying the people that do most of the work barely enough to survive. But legally they can do that. Morally they shouldn't. It might seem Morally right to pull a Robin Hood on them and give to the needy, but as I said, morals vary as many may view that as robbing people who worked hard to get where they are at while rewarding people that didn't work as hard. Moralality is like a double bladed sword. Each side think their side are the better morality. Unfortunately, sometimeso ne side have bit more greenbacks to give their morals an upper edge. And someone may that in itself is morality wrong. I think in a way it is.