It's a hard limit due needing fuel to maintain its orbit. It's in a lagrange point (https://en.wikipedia.org/wiki/Lagrange_point) which requires occasional orbital corrections.
Basically, because there is no reasonable way to service something in L2, they can't really plan for it, but it's expensive enough that they made sure there is the capability if someone in the future would, say, build a spaceship that is orbitally refuelable and designed so it can take crew that far out.