It's called give us the password to your Bitcoins (in this case, ill gotten funds), or face another 20 years in prison.
There are ways to resist to this.
See
https://bitcointalk.org/index.php?topic=323993.0 for a starter, multisigning is probably the best bet until some specific, unreplicable devices become reality.
There is no way to resist this.
Now lets fast forward some years and he has the choice to be a free man as soon as he gives the key or stay buried alive in a concrete room. How many nights will he go to bed knowing he could enjoy live and not have the door slammed closed behind him?
What good is x amount of coins with no access to it ever.
Also giving up the coins would be considered being part of the "rehabilitation process".
Of course the smart move is to accept the deal offered and get reduced time to start with.