Both of their reaction to nail art girl kinda makes me like them less. I'm speculating here, but it feels like a symptom of Japanese "fall in line, don't stand out" mentality. They're literally like "trying to change a school rule you think makes no sense and lowers your quality of life is stupid". And the whole "I like that the school rules here are strict", I seriously cannot imagine that this would have a good, rational justification if you tried to prod deeper into her reasoning here.