I looked briefly through rather lengthy minutes [1] of the meeting. Objections seem to come down to usage of words like "bitch" and phrases like "god damn" that students would get in trouble for using in the hallways according to existing school rules. The participants seemed quite queazy about saying the objectionable words themselves and instead either referred by their abbreviations or spelling them out by letter.
One part of the discussion that was also interesting was they considered censoring the book with whiteout for the offending words and one naked drawing but decided against it. They thought they need to get permission from the author because of copyright laws. I believe these kind of redactions are considered fair use for education under copyright laws.
[1] https://core-docs.s3.amazonaws.com/documents/asset/uploaded_...