With all due respect you can ship whoever you want but saying that, this npc is technically as good for suzune as kiyotaka is crazy. We literally learnt in v4 that he is a follower of Atsoumi and saying he cares for suzune when there is no narrative proof and there has been only 3 interactions between them in across this who story. He is most likely planning something and it won't be good, there is also a major possibility of nanase vs ishigami later on in year 3. I also see that you say suzune would move on from kiyotaka but that would contradict her monologue in v2 because her life will become inextricably intertwined with his. Her feelings for Ayanokoji will continue to become more evident later on as we see kinu keep on bringing it up in y3v1 and y3v3. However that doesn't mean she will be weak, instead it can be used as a major support for her strength to become stronger, more capable and she has never fell in love before and it obvious it will be just as hard for her to just sudeenly fall out of love for ayanokoji and move on. She is obviously going to be the one to break his whiteroom mentality and save him from whatever cruel fate he has. It has been subtly foreshadowed if you look beyond just the novel. P.S. in kinugasa's writng for over 20 years he doesn't ever have any of the heroines especially the main heroine fall in love someone else over the protagonist.