Back to the original post, I've almost finished Maus. It's very good. There are a few "shits" and an early discussion of premarital sex. Nothing I'd have a problem with for a 13-14 year old, but I know people who would.
But late in the book, there are two pages that cover the killing of children. One panel depicts a Nazi soldier swinging a 2-3 year old child by the leg, and bashing him into a wall. Its' black and white, but blood is everywhere. A few panels on the next page describe a mother who, rather than have her children taken to a concentration camp, poisons them. One of the children poisoned is the narrator's son, who we've grown attached to in the story.
I think it's reasonable to object to making that required reading for 13-14 year olds (remember THAT is what this debate is about, not banning the book). It's certainly worthy of a discussion. I don't know where I come down on that for my kids; I'd be fine with them reading it at 17-18, no doubt. My soon-to-be 12 year old son would be severely affected by it, though, in a way I wouldn't want him to experience now. My 14 year-old daughter--I'm not sure.
As a corollary, I don't think teachers or administrators have any more expert credentials or insight than any parent does over what their child is prepared to handle on an emotional level regarding that type of violence and horror.