The law makes it illegal for them to sell or possess the eagle art piece. You clearly missed the part of the article where it said that a special dispensation from FWS was required for them to continue possessing the eagle art piece so long as it was kept in a museum and was not sold.
I did miss it, because you made that last part up. You would be completely right if the article said "Mrs. Sonnabend was then able to retain ownership as long as the work continued to be exhibited at a public museum and not sold." But I just added the last three words. They're not in the article.
So, a special dispensation from FWS was required for them to continue possessing it. Which is illegal. So, ask for a special dispensation from the FWS to sell it to the museum. Which is illegal.
They have every reason to believe they will get it. Read between the lines.
