Might be valuable, but not the way they want.
Gov Brown of Calif has signed a law requiring schools to include "lesbian, gay, bisexual and transgender people, as well as the disabled, into the existing list of underrepresented cultural and ethnic groups listed in the state's inclusionary education requirements."
The LGBTQQABCDEFGHIJKLMNOPQRSTUVWXYZ part of this is just absurd, and students will understand its absurdity without any trouble. If the books are honest, students will learn that fags have always been big in the theater, which won't be news to anyone. That's all. I have no damn idea how you'll include "transgender people" in a history book, since they didn't even exist until 30 years ago. Unless you want to count the eunuchs who supervised Ottoman harems, or the castrati sopranos of the Renaissance. And I suspect those won't be counted.
The disabled part is
not silly, and if taught honestly will force students to realize something important. People with physical limitations have made great contributions to science, industry, art, entertainment and politics
in the past. Their contribution is drastically less
in the present, thanks to Rezident Bush and Comrade Bobdole's Glorious Soviet Achievement, the ADA. The purpose of ADA was to transform disabled folks from useful citizens to loyal litigators for the rapid advance of Communism, and it has succeeded quite well. Textbooks will, of course, say the exact opposite, but any student who looks at the facts will understand the truth.