Isn't it funny that characters that are sold to you as "headstrong", are crumbling as soon as the situation is actually diffy?
"Oh no, we're at a disadvantage currently right this moment... Abandon ship! Drop the nuke!!"
This is just a forced situation, because the author wants to do their thing:
Turn Euphie into spirit, Anis into dragon and then let the political discourse run around that.
The novel being so heavily loaded with politics and character development basically stopping early on, shows one thing:
This was always written around the idea of Euphie and Anis having to do the drastic decisions and what that would look like politically in that world.
The comments being split so strongly just show that the author failed in packaging their ultimate story outcome desire in a satisfying manner. This might even be a Manga-Reader VS Novel-Reader discourse.
Many people don't like it when !all! Characters have given up and are dragging their feet. If you don't actually portray the situation grim enough, then setting of the nuke seems just weird and out of proportion.
If you just go by the manga, the story fails quite heavily in supporting Euphies upcoming decision.