Silk has determined that he cannot allow the Bonneys to be convicted in the Court of Political Justice, but it's too late to have them tried as common criminals. A conviction would produce a precedent that would devastate the Diplomatic Corps by making every diplomat a legitimate target. Likewise, the Solar League cannot allow the Bonneys to go unpunished.
The last quarter of the story lays out the trial of the Bonney brothers. As amicus curiae Silk introduces evidence to show that the Bonneys assassinated Ambassador Cumshaw at the behest of the z'Srauff. He then persuades the court that it should not have tried the case, because Ambassador Cumshaw was not a politician within the meaning of New Texas law. Having thus got the Bonneys set free, he engages them in a gunfight and kills all three.