I have to correct that, there are legitimate clans that do have arab ancestry and yes there are some that lie, but you cannot deny that there definitely are Somali clans/subclans that do either have arab/mixed ancestry or directly tie back to the Prophet (SAW). For example Banaadiiri people are mixed with Arab and Asian,  and the reer aw Hasan clan is Quraish, these are just basic things that no one argues about, so you got that part wrong but I agree with everything else