it doesn't matter what they identify as, the rest of the arabs, and indeed the rest of the world see them as an admixed population of arabs and black africans, which is exactly what they are. thus they won't recreate the exact same type of civilizations or cultures that the arabs, nor the non-mixed black africans, did and do
implement your own advice, and apply proper context, "means very little" in terms of direct genetic effects into the people's behaviors and thus culture, because haplogroup genetic markers are not genes, period
and with regards to the topic at hand, my comments never left that context. the descendants of those melanesians that "become assimilated' into southeast asians, will not stop having the genetic influences of their melanesian ancestors, and will like the sudanese arabs behave as an admixed population, which is precisely how the existing groups of people that have both ancestry behave currently
a group of people choosing to identify as one group over another doesn't change that groups' intrinsic genetics or culture