Pluto

North No.2 was very much like humans when it comes to having genuine feelings and emotions, but unlike humans North had more appreciation towards life, whether it's plants, robots and living or deceased, like Paul Duncan's mother. Human's thought of robots as a tool, either for war or to fulfill a certain purpose like a certain job or task, robots are generally dispensable to humans except for a special case like Mont Blanc. On the contrary North respected every robot's life, thus he's always haunted by his nightmare of killing fellow robots, he sees robots and humans as equal. North also respects Paul Duncan's work and tries to understand him and help him explore the missing piece in his music, thus he went all the way to his birthplace Bohemia to learn about the folk songs. Whereas humans only know of Paul's glory during his days when he was famous and only wanted to reuse his works.

Question: Given the fact that robots were programmed to not harm humans but Brau 1589 did and no malfunctions in his system were found, what's your interpretation on why Brau 1589 killed humans?