http://www.reuters.com/article/2014/11/17/us-bitcoin-auction-idUSKCN0J11UJ20141117
The money at stake is the prize which the prosecutors are competing for, and to maximize his chance of regaining his freedom he'd want their incentive to be as low as possible.
I never understood how these US Marsals can auction these coins before at least one court officially finds him guilty. Is it normal in the US to sell these kind of assets before the end of your trial?
"Hey, I prooved I am innocent, so I can finally go home ... oh wait, they sold my house and took the money. Well... yeah..." Strange.
There is ugly shit called "civil forfeiture", but this isn't it. Presumably, Ulbricht is entitled to the proceeds of the sale if found innocent.