Good, I think. It was too political and would have made for bad precedent. Plus, it is just not that complex of a case. A school board has the right to prohibit a book as long as they follow procedures and do not discriminate. In this case, the factual accuracy of the book was questioned and (rightly or wrongly) the school board decided to follow their procedures to prohibit it from their school. Unless you can prove discrimination ... that's that. There is no First Amendment issue.
If you disagree with this denial of cert. by the Supreme Court or the current structure of the legal argument, don't get mad at the court - focus your attention on state legislatures that give school boards such broad authority to ban books.
Mark Walsh has more as always.