I enjoyed this story well enough. For much of the time that I listened it seemed like just another "robot is more humane than humans" story. But after further thought, it's something more interesting than that. Gahka is an incarnation of temporal culture clash. He is a long-lived creature instilled with the ideals of a previous generation left to deal with newcomers to the planet, and so we get to see firsthand (and without time travel) how representatives of these two cultures would deal with each other. I didn't necessarily see his actions as learning compoassions or ethics, nor necessarily that he was malfunctioning. I saw it that he had a set of objectives and he was fulfilling them as best that he could. He is programmed to deal with the scouting team, which are defined partly by their expected behavior. Once their behavior is shown to deviate from expected behavior, he logically concludes that they must not be the scouting team. If they are not the scouting team, he has no responsibliity toward them, and so he is free to do whatever he needs to to fulfill his responsibilities, and since these deceivers are interfering with his duties, his action is fine.
So anyway, yeah, after I thought about it further, the more I like it.