Plus in the end, after all that happened in Prometheus, still took an android who she clearly should know has a ethical issue, still lets him take her to gods doorstep. Putting all of humanity in jeopardy. I mean that is the pinnacle of selfishness.
She saved our a**es. If she had elected to go back to earth while david was still just a head, she'd have fixed him, gone into cryosleep, and he would've black goo'd us all. She'd been through hell, and after all that was seen, I'd want some answers to. If nothing else, she did it because she was curious, just like david, and there was nothing left for her back home. Charlie was dead. Her fault was that she allowed herself to be fooled by David enough to reassemble him and go into cryo.
Unless there's some unexplored angle like she was sick and he put her into cryo until they could reach paradise and its technology. It would be terrible to be awakened thinking that you're getting fixed, but instead you're getting filleted.