Why hasn't the King been disposed yet?
Think about it, it's not like the King has any major backup. It seems majority of Zhao, from the big name generals, majority of the soldiers in battlefield, the citizens / villagers in scattered areas of Zhao, even the idiot government officials in the palace.
All of them either supports Riboku and knows he is the biggest deal in Zhao, or just don't like the King.
So why is the King still not disposed yet?
They also should know Renpa left the country because of the shitty King. So if they kill the King, and make Prince Ka the next king, then who knows, Renpa probably will return to Zhao again.