I don't think they're legit. Why? Because my uncle in Somalia (who's the biggest Shaykh in his district and an expert on Arabian genealogy) doesn't think they are. I was in a Masjid one time and I've seen everyone kiss some man's hand (who hailed from Ashraf Sarman, who are pretty much the same thing as these Dhamul Jadiid people), so I asked my uncle if he's from one of the accepted tribes of Asharaaf, he replied in the negative.