So you're having a different debate to what the article is about.
Do you think it's wrong for twitch to ban people for: "terrorist activities, child sexual exploitation, violent extremism, credible threats of mass violence, carrying out or deliberately acting as an accomplice to sexual assault and threatening Twitch or its staff."?
Banning a book isn't even in the same ball park. I think it's pathetic of the school.
And a private school "banning" a book isn't an actual ban. You could still purchase and read the book if you desired.