as far as I know, they have no right to prevent us from using our copies the way we want... I think they should be worried not us.
Interplay and Volition retain a lot of intellectual property rights that are pretty regularly violated by the FreeSpace community. I'm no IP lawyer, but nowhere has either company granted any of our unofficial the right to distribute or create and distribute derivative content. In fact, the final version of the FS2 EULA (that is, the one without the 'friends' clause) pretty explicitly prohibits such activities....
Interplay Entertainment Corp. and its licensors retain all right, title and interest in the Software including all intellectual property rights embodied therein and derivatives thereof. The Software, including, without limitation, all code, data structures, characters, images, sounds, text, screens, game play, derivative works and all other elements of the Software may not be copied, resold, rented, leased, distributed (electronically or otherwise)...
I know part of that has been revised by the license under which Volition released the source code, and though I need to double check, I believe that that only grants the right to distribute the source code itself and works derived directly from it. That would include the FSO and FRED_Open executables, but not the MediaVP content, which is rather plainly derived from the retail FS2 content.
I'm no IP lawyer, but if I had to venture a guess, I'd say that, if continued community distribution of FS2 is seen as cutting into a legal distributor's profit margin, server owners and administrators with FreeSpace content would receive cease-and-desist letters, with a court date to follow, should they not comply. If unsatisfied with that, they could then attempt to track down individual users, in much the same fashion as the RIAA goes after individual users of filesharing networks.
That's a worst-case scenario, rolling through my mind, though. If I remember those titles correctly, they're all games that Interplay distributed. It seems as though they're trying to reestablish some normal cashflow through digital distribution of some of their classic titles, which means they might be satisfied taking whatever they can get with a minimum of cost and effort, and lawyers are never cheap or easy to deal with. At the same time, I'm making a point not to lose my FS2 CDs, just in case someone in a suit comes knocking, asking questions.