So
Whats the point of all of this convoluted plot and politics?
Some greedy old men want to conquer the world and order the young men to die?
It appears to be the same case with many a political challenge - a zero sum game where one side must lose when others win.
A reminder that the Sharowa are meant to be in an internal struggle, one which they pulled Zenjirou (and by extension, his infant son) into. In this case, Zenjirou's purported anger is clearly the reason to tread lightly, else they'd essentially have given away an allied kingdom's support to the brother that Zenjirou (and by extension, the Capua kingdom) is on better terms with.
I think this arc establishes more instances of royal cloak and dagger setups, as each side tries to avoid being the biggest loser.