She is inexperienced and naive because she was raised by a conservative religious group. Taking that into account, 20 is about right.
Besides, what is the "age of consent" in the Sith Empire jurisdiction? Would a DS character even care?
I would rather expect that the Empire employs the opposite: a Point of Dissent: "When you can make me stop
, then I'll stop. Until then, you're weak, and deserve everything that happens to you." Indeed, perpetuating cycles of abuse seems just about the perfect description of both Korriban stories, doesn't it?