Apparently, he sent a letter which caused some people to be concerned.
From what I've read on the StarDem website (can't find the source for their info), the Wicomico County State's Attorney brought up the issues. From the LATimes article, people were aware of the books before all this.
IMHO, I think there's something else going on here which caused a lot of people to become really concerned. I don't get the feeling it was an overreaction but involves something that they can't share for various legal reasons.
My suggestion, wait and see what is happening.
I think everyone freaking out about an "Author" being taken away needs to take a step back, remove the "books" from the picture, and see if their reactions are justifiable because every article I found about the issue is going nuts about censorship but very few seems to be approaching it objectively.