I'm genuinely interested in the answer to this. It is definitely found in an elementary school? I can see that it is on the banned list, but are you sure this book was actually found in an elementary school? Someone in a position of authority then needed to specifically order it, and that would be a dereliction of their duties if they did so, and that would prove the "grooming" assertion.

Is there documented proof that this was in an elementary school?

This feels like an important question. If it isn't found in elementary schools, then there simply is not a teacher or librarian out there attempting to put books in front of elementary kids. And, then this whole argument seems like virtue signaling for political gain.