Not at all. There is an absolutely brilliant book, Illegal Tender that reconstructs the events surrounding these coins. There is no doubt whatsoever that they were stolen. It does not matter who they were stolen from, it is tenet of American Law inherited from the English Common Law that title to stolen property cannot be perfected. That means that ownership of stolen property remains with the person from whom it was stolen. This is why people are getting works of art back (or compensation in lieu of) that were looted by the Nazis. I learned this lesson when I bought some currency on eBay from a pawnshop in Florida that turned out to have been stolen from a dealer in North Carolina. I had to send it back to him and eat the loss myself.