You know very well that many qabilist somalis wouldn't consider that person as Somali no matter how close Afars look to us.Huguenots are French people, racially and ethnically close to the English. It would be like a Somali who is autosomally mostly Somali, but with an Afar paternal lineage (Somali scenario of Nigel Farage).
Somalia is also not a nation of immigrants so it's different.
Anyway there are Yemenis born in Somalia who proudly say they are somalis, nothing wrong with that. There are some arab yemenis who were born and raised in Somalia, many only speak af soomaali and hang out with Somalis in the diaspora. It makes sense for them to call themselves somalis cause it's their nationality even though they aren't ethnic somalis.