My point is that, unlike us, the MCs have no way of knowing. They can't read minds or hear the Word of God. (Superwoman jokes aside, the way they interacted during their flirting-but-not-yet-dating period makes it obvious.) I'm okay with Nikaidou taking back her declaration of despise and agreeing to "not hate" Kirigaya (cause Tadokoro would be sad otherwise, so she has no choice) but... befriending Kirigaya?? That's completely unnecessary and going way too far.
You seem to be underestimating the scope of Nikaidou's superpowers. More to the point, aside from hypothetical reprobacy being terminally stupid of her as already discussed since the Big N already knows what's up, Kiri already proved herself a very poor liar who's singularly unlikely to be capable of convincingly faking that level of emotional distress.
Seriously where do you people keep pulling this bizarre idea that petty schoolyard bullies are magically all sociopathic master liars who could bullshit their way through a psych evaluation, and why?
Probably safe to assume that as far as Nikaidou is concerned Kiri is for now "on probation" and will be kept an eye on until her bona fides have been proven beyond reasonable doubt though.