This kinda hurts to say, and this is def due to the dissonance between gameplay and story, but Kieran telling the villagers the truth about Ogerpon...doesn't really do anything.
The village head is a money-grubbing sellout. Japan does have an issue in real life in which their rural villages are becoming ghost towns due to everyone moving out to the cities, but some are getting by via appealing to tourists with their unique products and attractions. All Mossui Village has besides their orchards and rice paddies is the legend of the three heroes that sacrificed themselves to stop the rampaging ogre, and the village head isn't willing to let the false story die if it means the revenue goes with it. He pretty much explicitly says so to your face.
So who cares if the locals know the truth? The false story is the one still being advertised to outsiders, with the sign boards still up, the Loyal Three monument rebuilt, and Ogre Oustin' continuing. No wonder Ogerpon wants to go with you.
Carmine also admits her hostility is fueled by not wanting her home being reduced to a tourist trap, so uh, it's probably good that we never tell either of them this.