I'm glad Texas has a centralized textbook adoption board. These kinds of attempts to rewrite history get caught. Texas is such a big market that revisions forced by Texas get put in textbooks around the entire US.
The author, David Barton, is a Texan and consults with the state on curriculum. I saw him speak at a conference this past June. His talk on the Christian foundations of America's founding BLEW ME AWAY! The guy is encyclopedic in the breadth and depth of his knowledge. Spend a little time on his website. It's an eye-opener!