Which seems to conclusively prove that he may have drawn this in the 16 century, but a lot of it is based on much older information.
Which is hardly what you say he said...
The letter-writer was arguing that the map was drawn from information extracted when Antarctica was “very hot” and iceless, way way before any human conceived of a map.
It’s a full letter at the bottom, that was broken up to respond to. If you read the whole thing, the context of the letter-writer’s argument that the map was based on “much older” information is that the info came from when Antarctica was “very hot,” which is patently ludicrous.