No she is just insane.
First, age of consent does not matter here. They are still legally minors and you have an adult suggesting that these minors have sex.
Second, she is a TEACHER. Teachers are educators, and legally speaking they are in charge of students and, while doing their fuction, in a position of authorithy compared to the students.
She's supposed to be an educator and an authority figure, and she's telling one of her students to have sex with another one of her student. And even worse, she thinks the girl might have some problems or trauma or whatever and she's still encouraging the boy to have sex with her.
She is the ONE person that should never tell him to do so
What she's doing is a crime. This is not a same age friend telling him to have sex, this is a teacher, in a position of authority, telling him to go have sex with a girl who may have trauma or other issues. That' s just INSANE.
As we both agree, there was literally no need for any of this as they are already getting friendly and more, and so the author adding this is completely out of place and freaky...