What you've left out is that the people Siculus referred to as Atlantians in those passages were the people living around Mount Atlas in the Atlas Mountain range of North Africa. He states this in his description of the area surrounding the marsh that was the Amazons' home:
These people were the same ones written about by Herodotus hundreds of years earlier and are not even similar to what Plato described:
Herodotus' "Histories," Book 4 184
Hence, that's not Plato's Atlantis.
As mythology relates....so he connected mythology to it. But he doesnt state that is mythology when he say that Amazons attack Atlanteans.
From your quote of Herodotus:
Atlantians; and it is said that they neither eat anything that has life nor have any dreams.
Text Santi Parva spoke about Atala white island with white men who never have to sleep or eat.