I cant do astrophysics math but my guess is something to do with tide locking. Like if the moon is tide locked to the gas giant and its orbit is slow enough, it would always be on the dark side.
This is not what it means for a body to be tidally locked. The Moon, for instance, is tidally locked to the Earth. The same side always faces Earth as it completes an orbit.
What you're talking about is Lagrange Points which (I may be wrong) I don't believe are supported by the physics of the Elite Dangerous game engine. An object orbiting at L[SUB]2[/SUB] would remain eclipsed from the star by the planet that it is orbiting:
