Here's my two cents (posted elsewhere previously):
Since regulation looks imminent, and the DOJ is not going to be able to keep seizing payment processors after it's explicitly legal in the US, they're going for one big score before it becomes impossible. Especially since they know no one they indicted will show up in the US For court. They're just trying to get them to pay money for the promise that they'll be able to enter the US market again once it's legalized.