Alright, the plot of this chapter was severely rushed, so we didn't get to see things as they should have unfolded for Eve without Keyaruga's intervention.
Because of the rushed plot, the resolution to the problem Eve was facing had to be solved quickly, and that's where Keyaruga came into play, solving the issue immediately so the plot of the manga could continue faster.
I think if things had been allowed to unfold at a normal pace for Eve, she'd had spent months if not a year or more trying to talk and sway the Demons to agree with her view on how they should all behave going forward, it would basically have been so long that it would have had to be its own manga, and it would show all the plotting of the rebels, assassination attempts on Eve, Eve fumbling around like an imbecile thinking it is feasible for all the Demons to suddenly decide to be pacifists and live together peacefully, only for her to either get dethroned or finally realize and accept that some acts of violence will have to exist to have the best and most peaceful future for the Demons be possible.
Instead of all this, the Author probably plans to use Eve in the war arc that's coming, but couldn't just "pluck" Eve out of the Demon Lord Throne as if wished for her upon a star or a Genie in the lamp, because it was clear to the readers that she would have a lot of issues ahead of her taking over the title and position of Demon Lord, but they probably didn't care enough about the politics of the Demons to spend too much time on that part of the story.
Anyway, I'm done with this comment now