@HOOfan_1 You really think Eri has done nothing wrong? Need I remind you of the fact that Kimito is actually afraid of her because she regularly kicks him in the shins (probably the balls, too) and despite trying to convince himself that seeing her at Seikain was just a hallucination, he still planned to hide in his room until the next day. Then there's the fact that she constantly belittles and insults him in front of people, she treats him as little more than a slave at her beck and call, and is also the one who told the staff at Seikain that he was gay and had a muscle fetish. And all of that is because... Some other girl gave him Valentine's chocolate in the 4th grade. Those are all signs of a pretty abusive relationship; seriously, flip the genders and put Eri through the shit she puts Kimito through and you'd be cheering the moment she shot him.
While it's true that Eri's core messages, "think for yourself" and "don't take everything an adult tells you as absolute truth just because they're adults", are really important messages for these extremely sheltered ladies, the problem is how she went about it. She coached them on exactly how to act to be as disruptive as possible, as seen when she had those girls repeat that laughing pose until she was satisfied; we can then easily surmise that she coached them on every other aspect of their behavior. And that behavior
isn't how things work in the real world. It's how things work in a
very specific and relatively minor counterculture. If she just taught them that these things exist, it'd be one thing, but again, she deliberately coached them on how to act and wasn't at all bothered by it until they chased the teacher out of the room because she knew she was in trouble for starting it.
Yes, she tried to apologize as soon as she was dragged to the dean's office, but again: apologizing doesn't free you from dealing with the consequences of your actions. All the girls did by rescuing her was digging her deeper, because whether she told them to do so or not, all of their actions are directly Eri's responsibility, because if she hadn't taken things as far as she did, they never would have even conceived of something like that. Which is the exact reason none of them got spanked; without Eri's influence, none of them would have acted in such a disrespectful manner (and yes, everything they did was highly disrespectful and the kind of thing you'd be punished for in any school, unless they've gotten seriously lax in the last 20 years). Also, Kujou is the head maid (and, thus, head disciplinarian), so it's pretty obviously her job to dish out punishment. Is Kujou jealous of Eri? Yes. Did she use the opportunity for a little payback? Most definitely. Doesn't mean she was in the wrong for doing her job.
Point of fact: legally speaking, Kimito was not kidnapped as he is a minor and his parents agreed to the transfer (granted, they were bribed, but they still had no problem with it). The school also has a duty to protect its students, even if they weren't filthy rich; the fact that they are just means that the level of protection goes up exponentially, and the fact is, they would threaten anyone who intruded on their grounds with the same options: stay here or live in an unmarked black site for the rest of their lives. Eri only avoided that because Kujou came up with the NDA for Kimito's sake. Kujou
isn't attempting to push Eri out of Kimito's life; that's just a happy bonus for her. What she's trying to do is take control of a potential security risk. Remember, their location is a highly classified secret that involves the manipulation of satellite data and the cooperation of the highest levels of government; if Eri were the more malevolent type, she could easily lead hundreds of thousands of people right to their doorstep, and, in fact, that's exactly what she was threatening to do by recording Reiko talking about Seikain on her phone. Could you imagine what would happen to a person who waltzed into the White House and said "I have videographic evidence of your secrets and how to get past your security, give me something or else I'll lead thousands of people I know nothing about into the Oval Office"?
Yes, it's pretty screwed up that Kimito's given no right to refuse (but again, security risk), but since the reveal of Kujou's true nature, I believe the gay claims are just a convenient fiction for everyone involved; he vehemently denied being gay when first brought to the school, at which point the dean brought up the castration. Reading between the lines, it would go something like "we know you're not gay, but these ladies belong to insanely powerful families that will make your life a living hell if you touch one of them, so play along to give the parents' peace of mind"; the threat of castration seems more like a gruesome reminder to keep to the official story (and Kujou's way of ensuring no other girls get too close to what she believes is hers), though the dean may have actually gone through with it.