Because it's a non-story. In fact, it isn't even worthy of discussion. I doubt the school board went through and gave the thumbs up or thumbs down to individual books on a reading list.
And if you've ever heard the conversations on a middle school playground or a high school gymnasium, you'll know that anything written in that book comes off as tame in comparison.
It's a wedge issue. For largely white school district parents to get outraged about because..."What about the children?". If you haven't noticed, this is the new alt-right battleground.
The guy was removed (I'm guessing) because he was violating public decency laws.