You've posted a link that shows two pages out of a 245 page book. Do you have any idea what's in the other 243 pages? Maybe it's something that's legitimately educational. Is one steamy sex scene enough to decry a piece of literature? Because there are a lot of literary masterpieces that include sex. Is any sexual content enough to decry something as devoid of literary or artistic value? Are you the final judge of morality when it comes to sexuality in art?
Education touches on controversial topics. I had a conversation in a high school social studies class about bigotry where my teacher gave us examples using words like "lovely human" and "******." Clearly I can't say those words at work without offending someone; I'd probably get fired. But an academic setting is the perfect place to discuss controversial topics. Sure, people might get offended, but that's part of the educational process. Teaching a social studies lesson about bigotry without identifying examples of bigotry would be utterly pointless. Similarly, pretending that sex doesn't exist is an idiotic way to educate adolescents. You can't just stick your head in the sand and pretend that a 15 year old isn't going to have sexual thoughts; it's asinine. And if you assume that all it takes to open those floodgates and unleash a raging hormonal teen orgy is a single depiction of sex in a single book, you have no respect for the teenagers you're purportedly trying to protect.