It's worse, though, when elementary schools teach his exploits as if he was some sort of hero. It's white supremacist propaganda.
Generally, school curriculum is going to reflect the social and religious attitudes and beliefs of the citizens of the state and then the same even more so at district school board level. Teachers unions don't have a great deal of influence over specific curriculum. If the people don't want it their voices will be heard and changes will be made. Unfortunately, it would seem that the good people of Louisiana want to follow a very conservative Christian slanted curriculum. I certainly do not agree with any of the reasons in the OP and I would hope most people don't. It does seem that Louisiana may be more likely to agree with it than other people and places.
The truth is most school systems in America are pure crap these days. I live in Arizona, I think Arizona ranks 48th in education. Sooner or later, it's going to cost Arizona a lot of potential revenue, unless new or large relocating manufacturers and/or distributors are looking for dummies who will work at close to minimum wage. Louisiana is no different.
I refuse to accept the view that mankind is so tragically bound to the starless midnight of racism and war that the bright daybreak of peace and brotherhood can never become a reality. - MLK