thus proving at point that a shader can operate at ranges above 2^32.
There's a difference between "operate" and "operate well" - the main limitation is the depth buffer, which because of the way they work has an effective range of only around 10^6 (and is getting a bit flaky once you go much beyond scanner range). The whole two-pass thing was supposed to give us the ability to go beyond the limitations of a single depth buffer ... but it's not at all straightforward to get right!
OOPlanetEntity.m line 600 onwards used to switch between "near" and "far" rendering modes for the atmosphere as the distance to the planet approached 10^6 - this was a very visible transition, so it currently uses "far" mode all the time. That still needs fixing up, and may have something to do with this.
2^32 isn't particularly relevant - OpenGL uses 32-bit floats, not 32-bit ints - so you just get increasing imprecision with increased distance. The absolute limit would be somewhere over 10^38 but you wouldn't be able to do anything useful with it.