iirc, she was in the demo missions, and as a result, I thought she might have a role in WCP, but others here claim that she wasn't.
My guess is that either Stilleto's call-sign was changed from Amazon shortly after development started, or else she was meant to play a minor role within the game (like Spyder) and then got cut. Her inclusion with the pilots on board the Cerebrus is probably just as much out of deference to the role she no longer had as it is to fill out the extra slot on board the cruiser.