Final scene of the episode, it was more than just Data.
DATA: Unlikely, sir. Your collection has been confiscated. All of your stolen possessions are being returned to their rightful owners. You have lost everything you value.
FAJO: It must give you great pleasure.
DATA: No, sir, it does not. I do not feel pleasure. I am only an android.
Though you're right, while the Enterprise is holding him in the birg, doesn't mean the Federation arrested him, they could just be holding him for the proper authorities.