Your arguments have no basis in the law *as it exists in this reality. The law makes it a felony to sell or possess bald eagle remains. The only reason that family still "has" this art piece is because actual possession of the art piece lies with the museum; the family retains "legal" ownership but cannot ever actually exercise possession without violating the law.
The family does not have a reason to believe that a sale to a museum would be approved since that would be a clear exception to the explicit text of the law. The prior "exception" does not change this because it does not actually conflict with the terms of the law.
You need to either (1) learn the law or (2) stop pretending like you know what you are talking about. Armchair lawyers like you ruin the discussion of legal articles on HN.
I will just say that if it were me in this situation, I would never in a million years go on an art appraiser's word that I 'can't' sell it, without even asking the appropriate agency.
The family does not have a reason to believe that a sale to a museum would be approved since that would be a clear exception to the explicit text of the law. The prior "exception" does not change this because it does not actually conflict with the terms of the law.
You need to either (1) learn the law or (2) stop pretending like you know what you are talking about. Armchair lawyers like you ruin the discussion of legal articles on HN.