Let's be blunt here, it was a threat despite the spin being put on it. The basic point here being that before actually suffering substantial legal action they will close the servers. The basic point being that if too many complaints were being raised, and the goverment got involved, Activision would simply pull out.
That said, I actually tend to agree with the guy making the complaints. A lot of video game companies do take a very slapshod attitude towards their products, especially when it comes to multi-platform releases and platforms they don't think are quite as profitable and thus not worthy of as much work as other ones. Gaming is a big business and it does all the other things that other businesses do, and we as consumers have just as much of a right to call them on it.
Strictly speaking, there are a lot of legal issues connected to things like this that haven't yet been addressed, and probably should be. The servers being "free" is not an issue here, the issue is that one of the features your paying for is multiplayer, which is says right on the box. If that multiplayer is broken, and doesn't work as it should be, that's like any other shoddy or defective product being put out on the market. What's more, returns with video games is a BIG deal given that unlike a lot of other products you can't just take them back to a store and return them for a refund.
Right now EULAs when disputed in of themselves have done okay legally, but an angle that has yet to go to court in regards to video games is the lack of information on the package. Simply put, when you pay your money your typically not agreeing to anything other than what the package itself says. All of the legal stuff in the game can be considered debatable because you already paid BEFORE that came up, and your being forced to agree to it or lose the money you already paid since you can't return the product. As far as I can tell this has yet to be fought on these grounds. Technically, people should be made to sign the contract as part of the purchuse with that understanding. Digital distribution already does this as you have to "click off" on a purchuse agreement as you pay, but with physical media like console games this is hardly the case.
To be entirely honst, I have not looked at the Black Ops. packaging as I am not a FPS player. It however seems unlikely that the "coverage" Activision gave themselves in the EULA was clearly stated on the package (and there are laws governing fine print, ard marking an asterix or whatever for further information when it's not readily availible on site). Heck, I don't think I've ever seen a game with multiplayer that clearly marked that the company could choose to take the servers down on the packaging. As "ridiculous" as it might sound in a lot of places gaming companies are probably required to run gaming servers in perpetuity for that reason, and if questioned on this grounds things are going to get REALLY interesting. It never went anywhere because whining nerds do very little, but when Microsoft took down the old Halo multiplayer so they could update X-box Live, there was some discussion about what would happen if *SERIOUS* legal action was actually taken on these grounds, based on the packaging at the time of purchuse, especially considering that this was old enough for multi-player to be new and nobody had thought things through to quite that extent yet.
As odd as this sounds, I've actually been of the opinion for a while that both digital purchuses and games with online multiplayer should be backed by something similar to trust funds before they can be sold. That is to say that the companies selling these products should have to create an account as part of the development that generates enough interest to keep servers running and mainence personell (if required) availible indefinatly. This as a protection against the company itself going under, or something similar. You see with the kids of rich people, and certain charities that operate purely off of interest from accounts they hold. This would render the threat of something like STEAM going out of business, or a company not being able to afford continueing to maintain the "Demon's Souls" servers more or less irrelevent. Of course it does mean that a lot of smaller companis simply wouldn't be able to distribute digitally or create multi-player games, but as a consumer I'm actually cool with that as I'm not all that fond of everything going digital nowadays, and it would encourage a lot of smaller companies to develop single player, offline, physically distributed games which are what I generally prefer anyway.
I doubt it will happen, or at least not in the near future, but I'm always hoping that we will see what I'd consider a properly fought legal battle will take place (I think most suits on similar things pursued the wrong angle), and as a result the above is what we'll see, because honestly I simply don't care for the idea of being totally at the mercy of a corperation (and it's continued existance) for access to what I paid for.