Unfortunately, our passport has become worthless and when it was worth a lot more, the laws were different especially if the child was born and raised in Somalia. In Xamar, when my parents were growing up there were a lot of half Somalis with Yemeni fathers and those kids always had access to passports like any other Somali child with a qabil.
There is no denying that you are what your father is. Also those kids cannot say they're ethnically Somali, although they can say they're half or my reer Abtis are ect, however we need to note that ethnicity and nationality are different concepts. We can't be hypocrites. We have Somali cadcads and Bantus, Somali Yemenis who only came a century ago with 0 Somali blood with Somali nationality so denying a child with actual known Somali blood is clearly hypocritical. Even more so, when now a lot of Somalis are in the diaspora and are claiming passports of nations they have no historical or blood ties with.
Yemenis you mentioned had a historical presence in the country before independence. They are no different to the Somalis who acquired Khaleeji or Yemeni passports as they were long time residents. Poor comparison.
Somali Cadcads have been there for almost a millennium and built the cities they live in. Some Bantus like Shidle and Makane have a historical presence in the land, they have as much right to citizenship as Faradheer. The descendants of slaves had no choice in the matter and cannot be repatriated morally speaking. Another poor analogy.
As for your hypocrisy argument, there are no universal citizenship laws. It varies from country to country. The Law of the Land is jus soli in most Western societies whilst it is jus sanguinis (paternal) in Somalia. Diaspora Somalis are not asking for the host society to change its citizenship laws! We are a more insular society that place value on blood ties, I don't see why that should change just because some diaspora Somali females, who are mostly not going back, have bred with Ajnabis. Why should their children who were not even born in Somalia be considered for citizenship? Our identity is patriarchal and based on paternal blood ties. Females that marry out already know this, and to be honest, most don't really give a toss about establishing roots back there with their Ajnabi kids. Like your opening disparagingly pointed out, our passport is worthless so why the fuss?
A woman who married out is better instilling her husband's identity in her children instead of confusing them too much with their relatively hostile Reer Abti culture. At least the kids will be grounded and grow up with a more solid identity.