Wow, the MC has a bunch of pretty pointy objects to stab the princess in her neck and she does nothing. If she already decided to be a sacrifice again, why not take the bad guy with her?
So she would die, and she's fine with that.
But then Jasmine and Samoa would also be executed, and she's not fine with that.
And that's probably why Caid wanted the two of them to stay with Shirley, to keep her from sacrificing herself.
Now, there's a risk here, but there is no safe path; every possible path has risks. But both Shirley and Caid think that this is the best shot. And besides, both Shirley and Caid do truly care for the people of their realm, and so will (almost) always act in the interests of the people of the realm.
A good chunk of what we're seeing is a criticism of aristocratic systems of power (or rather of inherited power).
- Shirley and Caid fit the ideal of aristocratic rulers.
- But reality is frequently like Shirley's parents, and Princess Batshit.
- Which requires a revolution.
- But violence and upheavals of revolutions, even if they are for the greater good, also harm some innocents (e.g. Shirley's original self).