I wonder if this move is to put more pressure on Pagliano despite the immunity?
Good point. I would think immunity deals are based upon what you can say and prove, not what you know but don't tell. Pagliano could (we don't know) be dragging his feet or holding out. This guy could turn up the heat and/ or corroborate Pagliano's statements.
One way or the other, we wouldn't fly a guy in from a European prison because we were bored or bluffing. At least I'd hope we weren't that stupid. Of course, we also have Afghanistan....