You've completely misunderstood =)
For Kuzan, Sakazuki, and Borsalino - Aokiji, Akainu and Kizaru are not their aliases but their first names/surnames
no it isnt ye moron, that is called speculation
Yeah he's completely speculating, I think it's only to be more "feared".
They're not their surnames, they are really their aliases! Talking as a reader of the manga, these nicknames are related to the momotaro legend, but as a person in OP universe I agree with the theory of more fear for their enemies.