The Nile Valley civilization, even according to the suspect dating of western academia, spanned at least 3000 before the invasion of Alexander of Macedonia in 332 B.C.E.
Geographically, the distance between current day Egypt and Ethiopia is a relatively short distance of roughly 1300 miles.
The origin of the Ancient Egyptian so-called "hieroglyphics", or MDW NTR, are sacred symbols which have not been "deciphered", "transliterated", or "translated" to english, contrary to the claims of Young and Champollion; and their modern day adherents, that is those who supposedly study "egyptology". Any individual who claims to have the ability to "transliterate" symbols to english letters and words immediately suspect of outright lying. There is no way for them to confirm their own interpretation of hieroglyphics to english words. For example, there is no clear and universal definition for the english word "race". Multiple disciplines within western academia have dismissed that "race" has anything to do with biology or genetics, however, at least in the U.S., "race" is used by the state for political classification schemes. Works attributed to "Manetho" are frauds. Similarly, many have no clue what hip-hop artists are talking about, unless they are familiar with the culture; even then E-40, Mac Dre (R.I.P.), Black Thought, Mobb Deep, Suga Free, Kendrick Lamar, etc. constantly develop new words and meanings for "english" words that are not found in any dictionary. An individual would need to ask what the words mean or be intimately familiar with the culture to, potentially, understand what the words mean. It is impossible to convert a symbol to a letter or word without asking the individual who wrote the symbols in stone or in papyrus what the symbol means. No individual who claims to have the ability to "transliterate" or "decipher" MDW NTR have ever asked any African Ancient Egyptians what those words mean.
The word Ethiopian in Greek is derived from the word Aethiops, meaning
Of the burnt face. It was a generic term for black skinned people
similar to latin words like Niger, Hebrew words like Kush, spanish
words like Moreno or Moor.
I am aware that there are some black skinned peoples who are native to
Southern Egypt. They still live there even till this day; The Nubians.
He may have been referring to them or so it seems.
What is the position of modern scholarship on these claims?
The so-called "Greeks" are, at best, only secondary sources for any African culture or state; they are foreign invaders, not indigenous peoples of any part of Africa. By the way, Ancient Egypt is in Africa, not some fictitious military concept such as "Middle East", "Near East", etc.
It is not clear what the term "black skinned peoples" was intended to mean in the minds of the foreign invaders "Greeks". Ask them what they mean. The "black skinned people" the Minoans? Or any other "black skinned people" found in antiquity around this entire planet - before there was a notion of a non-"dark skinned people" - as no one else but "dark skinned people" existed on this planet, Earth. It is not physically possible to derive "black skinned people" from "mauve skinned people" or "pink skinned people" or "white skinned people". "black skinned people" are the original people on this planet, from which all other "__ skinned people" are directly derived from (without going into Neanderthal and Denisovan DNA found in Europe; the original Autraslian peoples, etc.). Thus it should not be a shock that "black skinned people", that is, the Ancient Egyptians are the first literate people on this planet.
Ancient African culture is not based on some arbitrary "skin" concept. "skin" fetish, obsession and history revisionism is the mind of people who view "black skinned people" as foreign to them, not as their parents, the origin of modern human beings, and humankind. Or, that somehow, the Ancient African Egyptians were not both "black skinned people", what ever that is supposed to mean, and "brown skinned people"; thought what they were not is "mauve skinned people" or "pink skinned people". The African Ancient Egyptian ancestors at least left no doubt in the architecture which survives today what "skin" "color" they are. For that reason, people have to try to claim Ancient Egypt from the the outside looking in - after antiquity ended, circa 332 B.C.E., from a foreign "Greek" perspective, who had nothing at all whatsoever to do with the origin of the African Ancient Egyptian hieroglyphics, as their is little if any primary source evidence that survives which demonstrates so-called "Greeks" were literate prior to their contact with the Ancient Egyptians in actual history, not mythology.
Returning to what you have termed "modern scholarship", you can find whatever you want given a predisposed notion of what you expect to find. From the perspective of African culture, the Nile Valley civilization is a single culture, spanning the breadth and length of the Nile river, further up south into Ethiopia's highlands, over 1000 feet above down north. Rivers are a highway for languages, foodstuffs, inventions, etc. The Ancient African Egyptians are the smartest people in the world during antiquity, as evidenced by the tens of millions of actual artifacts which survive from before the concept of Europe and "Near East", "Middle East", etc.
So, read the "modern scholarship" of "dark skinned people" and "brown skinned people" relevant to the Nile Valley civilization - even if you do not like or agree with what they are stating - to get a better sense of the culture African Ancient Egyptians, as those are the direct physical descendants of the African Ancient Egyptians, not foreign invaders peeking in from afar leaving their opinions for history to try to give greater weight than at best secondary source, visitor, student, military invader. A distant visitor or military invader can never compose an accurate account of thousands of years of history which occurred before their invasion or visit. Similarly, one cannot ask Greeks or Europeans or English or German or French or "Middle East" or "Near East" people what the meaning of the sacred symbols of Ancient Egypt in Africa are; none of them were there when the symbols were being carved into to stone to ask what they meant then; they can only guess, and at worst, simply lie, about the origin and meanings of the hieroglyphics of Ancient Egypt in Africa.