I think you missed the “often" in your quote from wiki. This study is telling us that Africans and Neanderthals are not able to produce fertile male offspring

I think you missed the “often" in your quote from wiki. This study is telling us that Africans and Neanderthals are not able to produce fertile male offspring when a male Neanderthal reproduces with a African female. This is a common occurrence when two different species breed. I do agree that it is extraordinary that the meaning of this discovery is not recognised more widely, but please do not place words in my mouth as to what this means.