Passing models around is not an issue, with this game being 2+ years old and growing older it is the only way we can get some ships from the past. Not all the ships made made it to a general release, and got pasted around that way. In some cases that is how they actually became available years later at SFU.
Credit is important if you are pulling from their work!
Not passing it around.
I know what you mean though, I have a few ships with great textures and parts I would like to be able to use. I don't use it because I have no idea who did it, and can not credit get premission (in this case I know now who did it be can not locate that person). I also have spent months looking for some one to get premission to release a ship even if I know the name, and the site is listed in the readme, as usually that site listed nolonger exist because of the amount of time that has pasted. Took me 6 weeks to hunt down the author of the Churchill, and got lucky there because I knew he was a 3D artist and posted at I few sites I also look at.
So you can share the ships as they were released, but no one can use them for parts/textures with out credit.