~2d was intended to imply effectively 2d for human activities, even airspace is probably closer to a layered 2d cake than true 3d like deeper space. LEO may be closer to an extension of airspace due to orbits and gravity. Still, due to the exponential growth with respect to the radius, there is significant room in LEO compared to anything terrestrial.

How does this differeniate space and the ocean in your mind? Humans cannot survive in either without some sort of vessel to provide a suitable environment.

My GGGP point was about "clogging" space with satellites, not about habitation. Space is so large that 100K's of satellites is still not clogged. I believe the SpaceX and AWS constellations are planned to get us pretty close to 100k iirc

Quadratic growth, not exponential growth.

I think it's cubic because they sum, polynomial either way, without considering other factors like potential for increased density the further out

Right; I meant the number of satellites supportable at any given altitude, not the number of satellites supportable up to a given altitude.