It might be plausible if any evidence was presented, otherwise it's very loose speculation. Many of the cowhands working side by side vaqueros were literal boy

It might be plausible if any evidence was presented, otherwise it's very loose speculation. Many of the cowhands working side by side vaqueros were literal boys (15-17) and very young men. In Texas it's very common to call a young man a boy. Currently it's a baseless accusation that it was a derogatory term, even moreso that it's racial. It's never been mentioned as such until now, well past the high days of cowboys.