I doubt the government would consider what they possess as investment funds. Remember that the bitcoins they have likely stem from illegal activities, so their inclination would probably be to sell them once there are no claims and if the court orders it, those assets will become state income. If the US government had a Bitcoin investment program, they'd likely make it public knowledge. After all, the money they manage primarily comes from taxes, so keeping it secret is unconstitutional.
Regarding the seizure of Bitcoin, I don't think it will be auctioned. The market has changed significantly since 2014, with a much larger trading volume, making exchanges very liquid.
As we can see on CoinMarketCap, Binance has a daily trading volume of over $6 billion, while the U.S. holds only $5 billion. They could handle it, but it might cause an instant dip and short-term panic. So, they probably won't do that since it would harm the crypto market they've already regulated. I believe it will be sold on a schedule, gradually rather than all at once.
https://coinmarketcap.com/rankings/exchanges/