You're right he frowns upon even mild disrespect at the same level as treason. The plebs cry for real fear while pretending it's love in the mass "events" for the TV....As far as his half-brother I think he sealed his fate with the quote "Personally, I am against third-generation succession,” he told Japan’s Asahi TV back in 2010. 
Kim Jong Nam said his father kept his parents’ relationship a secret, was close to the murdered Uncle and had spoken out publicly against his family’s dynastic control of the isolated state. Surprised he lasted this long.