Still, even for the sake of research, teachers are not supposed to ask questions to their students about sex.
Part of the teacher training is warning you about not sexualizing your students and put the proper distance between you and them. That kind of topic should be reserved to a sex ed lecture where there's no ambiguity.
The situation here, with a teacher talking about sexual practices alone with a student is borderline creepy and were it not fiction, akin to sexual harassment. Even if he acts detached, he still sexualizes her.
I wouldnt call it sexualizing her it's more like research and study, and he says that to them. He also said that he became a teacher in stead of a biologist because he would have a better chance at talking to a demi because he couldnt get permission to conduct tests on demis. So in short is less about sexualizing them and more looking at them as test subjects( but more humane)