The issue with this is that it invalidates the definition of being a black American too.
Keep in mind the first Boers arrived in South Africa in 1652, only 30 years after the first slave ship arrived in New England in 1619. Whites have been out there for nearly half a millennium and nearly as long as African Americans have been in the US . At some point they are no longer guests, but rent paying residents.
I agree that Elon can't be black. But that doesn't stop him from being a white African, anymore than Habibi in Egypt cant be a Arab African or can stop Hindu-African Rajesh in Tanzania.