OK, so you want to play the game of "Hypothetical vs. Things as they Really Are."
Hypothetically, Neptunian Squid Men attacked Earth in 1953, not to conquor and enslave, but to eat all of the gold that they could find.
The Squid Men, in fact, ate EVERY atom of gold worldwide, leaving the United States and the rest of the world struggly to find a new commodity upon which to base... well nothing, I guess... but the worldwide decision is made to use zinc.
Is, then, the family of Israle Swit, dealer in stolen items (alleged), legally justified in retaining their memories of these coins even if they (allegedly) didn't know of their existence until post 2000?
OK, that was painfully... "fun."
Fact: 6102 was enacted in 1933, and subsequent acts of Congress in 1934 and after.
Fact: No lower court has ever found those acts to be unconstitutional.
Fact: The Supreme Court has never taken up the issue of the constitutionality of the actions that outlawed private possession of gold.
Fact: In the American sytem, the Supreme Court is the final arbiter of that which is, and which is not, constitutional.
Fact: Until the courts rule otherwise, Presidential Executive Orders and Acts of Congress are constitutional.
While nothing is impossible, nothing changes the previously stated salient facts that the coins in question were determined to have been removed from the Mint illegally, those coins were never released for public use, and those coins were never monetized, making them illegal for the public to possess.
Is it possible that the Supreme Court could, eventually, rule that the family was somehow deprived of their Constitutional rights?
Yes.
Is it likely, though, given the nature and history of the coins, that the courts would return those coins to the family, given that no matter how the Government treated the family, they are still the proceeds of a theft?
Very, very doubtful.
At best, I could see the Government being forced to renumerate the family at the 1933 per ounce gold value of the coins, about $25.
But will the coins be returned to the family?
No.
Should the coins be returned to the family?
No.
Should they be allowed to profit for the illegal activities of their relative at YOUR (and my) expense?
In what kind of crazy *expletive deleted*ed up world would anyone say yes?