Something I don't quite understand about Horikita's decision in Y2V5

because she never assumed or speculated that she could lose Kiyotaka's support with her actions? As readers, we know how Kiyotaka thinks, but Suzune doesn't have that advantage since, from her point of view, she saw how Kushida tried to make a false sexual harassment complaint against him and has been scamming him to give her half of his private points through a fraudulent contract, and she was 100% willing to expel someone she believed to be a close friend of Kiyotaka's in order to keep the person who harmed him, especially since he wanted to expel Kushida and already had a plan in place. At that point, Horikita was well aware of Kiyotaka's abilities and his participation in the class's strategies, and at that time, they were friends.

It also doesn't help that in her monologue, it seems that Suzune wants to keep Kushida more for reasons of pride and ego than because she genuinely believes he can serve the class.