This entire thing is ridiculous on so many levels is defies belief.
Bethesda pretty much gave the community a go-ahead to mod their games and even tends to provide the toolsets to make it easy to do. The guys making these mods were by and large adding free works to the community, and I'm pretty sure that by definition they don't OWN anything, since all their work using that game and the tool sets actually belongs to Bethesda, who by all accounts has covered itself heavily in this regard.
Claims of copyright would be bogus anyway. I'm not a huge expert on it but it's not quite as easy as a lot of people think to have a copyright stand. Simply put to hold a serious copyright costs money and you have to have it officially registered. A company that does not pay to maintain their copyrights will see their work become public domain, long before the simple passage of time would have a chance of doing it. Before anyone starts griping about how I'm wrong, I will point out that there have been a number of fights over things like this in regards to sites distributing "Abandonware" and so on. By and large they continue to exist because of companies not maintaining their rights and ownership of certain properties in the face of the law.
The whole thing about being able to mark "copyright" on something you create and then have it be protected has some validity, but mostly comes into play in cases where your on the way to have the copyright registered. The principle being that if you write something, and your roomate goes "wow, that's really good" and decides to grab a copy of it and try and get it copyrighted before you and gets there first due to having a faster car, you can protect your work from theft by having declared/marked that intent. Of course like anything there is no way to detemine the validity of when a copyright was marked, or who might have done it first. Anyone can claim anything is copyrighted at any time. Typically such marks have weight when there is some additional way of proving their validity. Back when I was in college the subject was covered in brief, and a simple and straightforward way of protecting a copyright in the short term is to write that intent on the documents (like a story) and then mail a copy of the documents to yourself through the postal service. The postal service will date the envelope/box and then as long as you don't open it you have an item dated by a third party with no vested interest that can show when you made that claim/created the work. So if you went to court over it, the package could be opened in front of witnesses. If the date marked by the postal service (and confirmed by their tracking system) is earlier than the guy trying to claim your work can prove he had a claim, your likely going to win.
Or in short, there is no way any of these mod creators could ever PROVE they created any of this stuff. I could take any one of those mods and say I made it, stamp a copyright on it, and who is to say they aren't robbing me, if there is no independantly viable proof? If they actually tried to pursue legal action here they would likely be laughed out of a courtroom. Not that the guy assembling these mods did try and claim them as his own or anything, he was apparently giving credit where it was due.
What's more, as I understand things, the guy putting together Morrowwind 2011 wasn't just using someone else's work and compiling it. Apparently he himself had to do some work to get all those mods to work together seamlessly. As anyone who has modded a game, even one designed for it like Bethesda's games can tell you, mods conflict with each other like crazy in some very unexpected ways. The guy does deserve credit for getting all those mods to play well with each other so to speak.
The point here is that this strikes me as being bogus, I think what we're looking at is a bunch of mod makers who were distributing their work for free, and who were being given credit for their work (which is the only thing they could reasonable expect) were trying to make noise because they could.
My big problem with the issue here is that Bethesda itself apparently banned the guy and took action on his account. Truthfully I think if anyone needs to be looked at carefully here it's them, because they shouldn't have been involved in this to begin with, unless in some way their ownership of the "Elder Scrolls" property itself was being threatened, which hardly seems to be the case.
My attitude is pretty much that a few arrogant twits with delusions of grandeur and non-existant legal backing, should be allowed to ruin things like this for everyone just because they can.
This is all simply what I think/have learned, and my opinion of course. Also I'll state that I don't want to get into a prolonged arguement on copyright law. It's been a while, but I tend to trust my sources. What little I know actually comes from my ambition at one time to become a science fiction/fantasy/horror writer, and having talked to a couple of english teachers in college about it when I was younger. The cost of copyrighting a manuscript was something they mentioned (if a publisher doesn't buy it from you and worry about that themselves) along with the bit about mailing a manuscript to yourself to use the postal office as an impartial third party as far as dates go as a defensive technique if you ever became worried about someone stealing your work. As well as a good thing to do in general in case when you wrote something comes into question (such as a case where another writer with similar ideas decides to try and accuse you of plagerism... having written yours first and being able to prove that is the best defense you can have).