The first page says heavy meritocracy, but it's actually not that heavy, it's rather a conditional one. Otherwise it couldn't be a hereditary monarchy. Because it's all but assured that somewhere out there would be a person more talented to lead the nation than the few children the current king/queen might produce. If it's meritocracy, the best person should be the monarch, not the previous ruler's children, unless they just happen to be extremely talented by pure coincidence.
All that being said, a king's less talented child should absolutely be kicked away. The monarch has the most public and important "job" in the kingdom, so any rules of meritocracy should apply to those queueing for that job thrice as much as to anyone else. If the rulers skimp on prioritising talent, why would anyone else do that then?