The great irony of it.
Cassius Clay rejected that name as a slave's name, and took the name Muhammad Ali as a 'free' name.
He took the name from a tribe that was probably the greatest black slaving tribe of all time: Muslim Arabs, and he rejected the name of a white man: it was 'white men' and they alone who ended the slave trade. The first time in history that slavery had been opposed by organised authority.
So, Cass, your adopted name says that you rejected freedom and returned to slavery.