The most favored son had actually been killed by Duoluo a long time ago. The news had been kept secret and not reported. It wasn't until the army returned to the city, and Regicide, while still clear-headed, sent someone to summon him, that he found out his most beloved son was already dead!
He was already severely injured, and this blow struck him so hard that he cried out, spat a mouthful of blood, and fell back, completely losing consciousness!
Regicide was aware that once he died, none of his sons could restrain Moxie. He wanted to use his remaining influence to have his most favored son take the most important thing in the Royal Palace, ensuring that as long as that thing remained within the family, there would still be a chance for resurgence. But he never imagined that someone had made a move ahead of him, killing his most loved son, and stealing the Bone Whistle!