But at least on the information we have to go by at the moment, the depiction of senpai as some sort of predatory child-abuser is not supported by the present evidence. Miyuki is what, two years older than Asuka? And Asuka has known her longer than she’s been friends with Jun and his family—she was shy Asuka’s first peer-mentor/protector.
Not sure who went on about child abuse (considering they are close in age), but she still sexually harrassed her at the very least. I would say kissing gets brushed off far too easily sometimes.
And you don't develope hate or strong dislike like that for nothing.
Without getting into a quagmire about when an unexpected kiss counts as “sexual harassment,” it’s clear that Asuka now sees Miyuki as a “liar” and an untrustworthy person, and for Asuka, who seems to have, at most, one real friend at a time, that’s a strong judgment.
But what actually happened with them besides kissing and some clothes in disarray remains to be seen.