The government should be allowed to refuse to sell items that have significant historic value, but the owners of such property who acquired it by legal means and with no ill intent should be compensated for the fair market value of such items if the government wants it. The government should not be allowed to merely seize the property. However, the government should have the right to such property after compensating the owner in the name of preserving national treasures or items of significant historic or cultural value.
Some things have a value that goes far beyond just monetary value. The bag that was used to collect lunar samples by NASA is once such example. When something is so important to scientific research or history, it is reasonable that the government would choose to intervene and prevent such items being sold.
Of course, they should be! The unfortunate mix-up is not the first time an iconic moon-landing mission artefact has made its way to wrong hands. Just last year, Neil Armstrong’s widow, Carol, discovered a bag containing various mementos from the Apollo 11 mission—including a camera used to capture the first human landing.
Yes, the government should be allowed to refuse sale of items with historic and/or scientific value because it will do the government a lot more good to have the item than if an individual kept it in his or her house. The government can now give it to a museum.