Even if the head Matriarch had a feeling the power the young king had displayed was not something he could hold for long, she still didn't want there to be a conflict. The original intent was to make him feel bad and indebted for his actions.
There was never really the option of war in the first place. Themiscus had long since fought an actual war, and the peace the kingdom knew was not something the current head Matriarch wanted to break.
The earlier threats were mostly empty.
Of course, they were war ready, if the need ever arose. But the entire kingdom had enjoyed peace for a long time, and unless a major threat appeared from an unseen realm, it would remain at peace.
Even if some smaller kingdoms had fallen to the recent waves of strange beasts and monsters, Themiscus never felt threatened by them.
At best, they made for the perfect training dummies. At worst, the weaker kingdoms got culled, and made room for stronger nations to grow or rise.