The only reason it isn't "conclusive" is because Meroitic in itself and Nilo-Saharan languages as a whole aren't understood well enough as opposed to Cushitic languages. The mystery behind them makes it so that new evidence for a Nilo-Saharan classification can always be challenged. I've seen both good arguments for and against a Nilo-Saharan classification but a Cushitic language doesn't seem like a language that would be
prominent among the ancient Nubians. Obviously Cushitic languages would've existed, it would be near impossible to argue against this, but they would have been small in number and more common among the eastern desert populations as I mentioned earlier. I believe until there is evidence to say otherwise, Nilo-Saharan languages would have logically constituted the majority of Ancient Nubia with the exclusion of the Pharaonic language.
May you link these skeletal records, I am yet to find much on this. Also, I don't deny a diverse field of Eurasian admixture existing among ancient Nubians, I am simply acknowledging the Modern Nilotic connection. Interesting stuff about the curly hair, I'd also want to see a link on that it sounds pretty cool. I also prefer to dismiss anything that uses "Caucasoid" and "Negroid" as if they hold any sort of scientific value in the modern age.
I am referencing this study that dates admixture in Nubians to mostly be attributed to peninsular migrations which logically means reversing this effect leaves with an ancient population that would have
some individuals with near to no genetic distance to modern notes if the West African affinity in Nilotes is ruled out. Also focus on how I mention "some" I am not arguing Kush was a homogenous playground for Dinka people.
Northeast Africa has a long history of human habitation, with fossil-finds from the earliest anatomically modern humans, and housing ancient civilizations. The region is also the gate-way out of Africa, as well as a portal for migration into Africa ...
www.ncbi.nlm.nih.gov