He's a sheltered kid. He has this idea of what life with the Gekkostate is. He has his idea of what flying an LFO is. He dream is to live through these things.
But he's sheltered, and he doesn't understand the real repurcussions of what the Gekkostate do. He doesn't understand the real repurcussions of their actions. He at first simply gets to live what is essentially his fantasy. The whole point is he's completely oblivious to the whole thing until it slaps him in the face in the worst way possible.
He has no reason to feel good about killing those people.