Beause the coins are worth millions to someone and also have historical significance. The best thing would be a settlement where they sell some of the coins and split the proceeds.
Really, that would be cool. Each group of 5, slabbed as "Gov't Seized" and "Langbord 5" or whatever. Let the prices realized determine which is valued more by collectors. Everybody sorta happy. Perfect.
That's what they were hoping to get. It's what happened in the case of the Fenton (Farouk) coin. It's in the opinion... "The Government ultimately settled with Fenton, agreeing to sell the coin at auction and divide the proceeds equally. The Fenton coin was auctioned in 2002 for nearly $7.6 million. [...] In 2004, the Langbords’ counsel informed the Mint about the Double Eagles that the Langbords had discovered. The Langbords sought an agreement similar to the Fenton coin compromise."