I'm just saying the specifics of what they're talking about aren't things that should be considered "being extra careful", they're blatant violations of other people's autonomy. Using your example, it would be like if I as someone who is both big and tall is told "People might find you more imposing, so you have to be careful and not punch them directly in the face." Its a bizarre implication that the thing they're being told not to do is only off limits because of what they are, instead of it just being a morally abhorrent thing to do. The blonde succubus is even shocked that she could be arrested for magically sexually assaulting someone. I feel like the succubus need to be taught basic ethics as a framework for their succubi-specific situation, and that isn't the vibe this lecture gives.
I mean, they don't simplify it to "be extra careful", the point the teacher makes is "we have to live more righteously than humans because otherwise they'll paint us as demons". And the connotation there is that
all succubi would suffer as a collective and be "other'd" by humanity if they weren't so rigid in self-policing the usage of their powers. "Demons" in that context are frightening nonhuman monstrosities that pose a threat to people, and the teacher is saying that succubi have to be mindful, and go above and beyond even what would be expected of "normal human folks", to ensure their conduct remains above reproach.
Which, again, is the important bit—yes, it's baseline ethics to not do bad things to people or to violate their autonomy. But it's
more dangerous for succubi, because they're already "not like normal humans", and have to be aware of the historical prejudice placed upon them because of the specific nature of their powers and the lore/facets of what succubi are. If one of them fucks up and causes issues, it comes back on
all of them, not just that individual. People IRL have an amazing record of being outrageously prejudiced toward things that they don't understand and thus fear—it's how racism exists in the first place. So the through-line of succubi having to go the extra step due to their inherent nature opening them up to more scrutiny and suspicion from humans means they have a higher hurdle to clear to maintain good standing in society.
To your last sentence—they absolutely were taught stuff like that, the teachers says as such in this very chapter. Rinka's just a special case of not having listened/internalized it seriously enough. Maybe she's a bit of a moron, maybe some aspect of her upbringing makes her feel like she's "above" things, but that's an individual problem of hers that she has to grow out of, not a systemic issue of succubi.