I disagree.
In this case, the parent wanted the book out of the school based on religious complaints -it offends her sense of religion.
Not that the books were too mature for the kids, or poorly written.
Religious reasons.
If people like that win, the Bible is next.
It doesn't matter what their reason was, they have every right to take actions and how schools are run. Just because someone articulates a Christian arguement, it doesn't mean they shouldn't be allowed to voice that opinion. It's OK for Jews or Blacks or Gay to voice objections when they are offended? Are Christians second-class citizens that don't deserve the right to speak their opinions? That seems to be what you are saying.
Of course it is! The Bible offends muslims, and unlike a Christian, a muslim is much more apt to express his displeasure with the local school board in a decidedly unambiguous and lethal fashion...