Thanks for the ping. I think he makes his point that Sundaland was inhabited before the rising sea level flooded it at the end of the last ice age, but not that Sundaland was Atlantis.
According to Plato, the destruction of Atlantis was a tectonic event that happened in a day and a night. Perhaps it was like the event that formed the Tula Rosa basin in New Mexico, in which the top of a mountain range suddenly dropped at least 4000 feet.
The weight redistribution from the melting ice would have caused giagantic earthquakes, volcanos and tsunamis all over the world. The northern areas of the world are still slowly rising and some southern areas are subsiding because of the weight redistribution.