Herndon is the town where all the illicit money-laundering Islamic "charities" were located, and IIRC there's a new large Saudi funded mosque there (or was that Leesburg).
I wouldn't be at all surprised if someone's on the take for this decision, because it hasn't happened elsewhere in NoVA.
At that site you will find information about which textbooks are a problem, sample pages from the textbooks, news articles confirming the information, testimonials, etc. Here is another good link..