From the viewpoint of the judge - this may be a thing that he sees needs to be properly defined in court, so as to set precedence in cases like this. It's not as simple a matter as "oh it's just junk NASA threw out", and NASA's response even out of court could effect more serious matters that come along.
Frankly, Ross's judgement of NASA's actions is something I expect from a child, not a journalist. A good journalist reports in an unbiased way, doesn't give a whiny 2-bit opinion from a narrow-minded view of the world. I'd say that he has some excuse in light of the low quality "journalists" we see on television, but then we are all ultimately responsible for our own actions, so he has no excuse in the end.
Do I think he should be allowed to keep the memento? Certainly. Do I think he should be allowed to sell it? As long as a clear, legal procedure will define the new owner as having clear title (something this legal stuff will do is help not only establish clear title but add to provenance, proof of what the item is and where it came from), it would be his to sell, and I have no problems with that.