I might be mis understanding the technical side of it
But isnt the idea the poster is talking about is that the Jump point could be its own "map" to travel through rather than an loading screen.
This part
"Server meshing means star systems will not be monolithic spaces but discrete boxes of space handled by different server instances "
Seems to suggest the opposite to your
"There is zero gameplay or technical reason why CIG should make seperate systems all part of the same map."
So you are both on the same page
Both systems separate map and the poster adding a third map for the jump point transit between them
All the other stuff seems to be about making it a seamless transition from the point of view of the client as it is passed from one server to the next.
Whether or not the wormholes are themselves maps or just effects, they seem to be saying that different system maps are joined like contiguous maps. My point is, i don't see any reason to do it that way.