Frankly I'm wondering if maybe these parents just have a problem with their kid reading, period.
I'm amazed that in 2012 people haven't yet figured out that if they don't want their offspring to read/see/play with any media all they have to do is use the magically simple word "No." Or a variation there of: Not now, I don't think so, after I see it first, maybe when you are older, Let's talk about... etc. Instead of controlling ONLY their family situation they feel the need to control everyone else's. Claiming to be concerned that certain media will cause their children to have a bad life, parents don't realize that by attempting to control every little thing in the larger environment they fail to teach their children how to make good choices on anything - let alone the media they consume.
There are books I don't want my kids to read. Books that consist of regurgitated licensed crappy characters where the story is supplanted by glittery stickers. We do read these occasionally but a lot more get accidentally left in the car. Maybe I'm a book snob, but I also don't let my kids eat Twinkies every day. I have explained (read: defended) my choices in both snacks and books to my children on numerous occasions. What I hope I'm doing as a parent is teaching them to choose wisely from the vast array of life spreading out ahead of them.
However what I don't do is march down to the library and demand that this book be withdrawn because it offends my literary taste and values. Some people like - even value - getting to eat Twinkies every day. I'm sure the Twinkie manufacturers are grateful.
While I must roll my eyes to the back of my head over these parents being concerned at their child seeing a boot covering a butt, maybe instead of taking up everyone's time and tax dollars they could have actually had a conversation about the book with their child. Then (in the unlikely event) when the little boy said "yes this picture makes me want to look up all kinds of nakedness on the internet!" they could have unplugged household computers appropriately. Or (more likely) when the boy seemed not to notice the almost nudity AT ALL, they could have sighed with relief and gone back to their regularly scheduled lives of shopping at Walmart, watching American Idol, and sending donations to the Family Research Council.
Being an illustrator, I'd love it if one of my books were banned. Sales of banned books always go up. Maybe I should start looking for manuscripts where I could draw a little bootie.....