The claim is that the greenish space makes dark objects appear more easily, and I know the “realism/fidelity” claims were clownishly wrong considering the space-fascist future features hand carts (that you have to buy with real world money!) and a star system loaded with 90s malls with hot dog stands, but something about making space itself a soupy greenish is… well… 
In the current version of the eternal pre-alpha of Star Citizen, if you don’t visit those space malls regularly and eat a space hot dog every few hours, you die. That’s fidelity!