Going to be honest, when I first opened the first page I thought the suggestion was to make Black people non-Human and their own race with unique racial statistics.
Being serious, if the addition of non-Human races are added for the Marines, it'll become nothing more than a slippery slope until other, more disturbing, races are added.
For proof, I invite you to check /tg/station's decline into catpeople over the years. I think they removed them though, the point stands.