This is pretty revisionist. Slavery wasn't some ancillary factor that just happened to exist in Texas. It was core to the anglo side of the Texas revolution. The War Party was strongly proslavery and the increasing (Mexican) federal push towards abolition was a key point for them. They especially hated a Mexican predecessor to the Emancipation Proclamation called the Guerrero decree that (attempted to) free most slaves in the northern states. After independence, they wrote slavery into the constitution and some of the first laws passed prohibited slaveowners from freeing slaves without government approval. The events in Texas were just one of half a dozen revolutions opposed to Mexican federal centralization around the same time.
None of this was politically palatable after the American Civil War and people certainly weren't going to focus on the non-anglo sides of the revolution that weren't so deeply proslavery, so the narrative that's taught in schools was sanitized.
None of this was politically palatable after the American Civil War and people certainly weren't going to focus on the non-anglo sides of the revolution that weren't so deeply proslavery, so the narrative that's taught in schools was sanitized.