"I, too, agree that Olympia would make a fine member of the Elite Four... and if any of the current gym leaders were to be promoted, my vote would go to her. I mean, she predicted the situation in Geosenge Town, the awakening of Xerneas, my meeting with them, and the lasting effects from it all with frightening accuracy. She is an irreplaceable part of Kalos' protection,"
"However... I must play the devil's advocate. There is no way to replace Malva with her without it coming off as a slight to the former. And I do not want all of those months I spent building up some sort of amicability with Malva and the few former members of Team Flare that survived wasted. More than Olympia becoming a member of the Elite Four, I want to keep the remnants of Team Flare at bay."
"...And I think firing Malva would be the quickest way to ignite all of their anger. Besides... her involvement with Team Flare was never public information. We owe it to everyone else to continue protecting Kalos from forming further cracks-- even if it means keeping her in the League until she wishes to step down. She, and those surviving members, at least has a code of honour. Malva was willing to do whatever was in her power to aid in Xerosic's arrest when he stepped out of line."
"I also do not want to have to deal with the fallout-- she would most definitely come to voice her displeasure and feelings of utter betrayal, genuine or fake, to me."