Hearing Angus' words and tone, the Duchess didn't correct him since this is true. Angus may be obligated to help and respect the Crown Prince inside the Heart Kingdom. But, here is the Nirvas Kingdom. No one could force him to do the same thing.
Besides, Aunt Extalia also agreed with Angus' words. As an experienced combatant, she knows only the strong are respected in this world, not the others around. This is proven as there are no weaklings among the nation's leaders.
Every strong person will never bow their head easily to others, especially to the weaker one. After observing Angus for a while, Aunt Extalia also noticed Angus' pride and behavior as a strong expert.
These kinds of people will choose death rather than bowing to someone they don't want to. On the contrary, if they find someone worthy of their respect, they will bow their head willingly, even if it is a thousand times.