I already suspected they'd drag up the "Stockholm Syndrome" again - an easy explanation for a complex problem. From all that I read, it tells me it's NOT Stockholm Syndrome though.
This is a girl who was abducted when she was 11. You can bet that for the first few years, she would have had zero contact with anyone except for the guy and his wife. This is not so much Stockholm Syndrome where the victim mentally forces him to go with the "dangerous" side for safety-sake but far more a case of simple over-exposure to a different world. We're talking about years and years of exposure during a crucial phase of human mental development.
After all, at the age of 11, kids are already creating an identity for themselves. Parents will know that it doesn't take much for their teenager to suddenly behave in completely different ways. Because she had no friends or society to find inspiration, she had to make do with what she had.
Now, when your only environment is a guy who is older than your father + his wife, you can only grow within that frame. Heck, there's plenty of children who live with abusive fathers and mothers and who just grin and bear it. They are hardly Stockholm victims as well. It's simply a case of being used to the situation and making the best of it. In the end, she only knew that life and humans are always averse to changes so it's natural for her to stick with the guy. She most likely no longer considered herself a captive but part of his family and in that frame of mind, she may have accepted her captors behaviour.
Also, it's not impossible to sympathise with someone who has mistreated you in the past. There's thousands of examples if you look around! Heck, several cultures around the world still allow the selling of 10-12 year old girls to wealthy men to marry. In the end, these girls grow up and become faithful wives even if they were abused.
Anyway, this case is interesting from a psychological point of view. I think she's going to have a very hard time adjusting to society again and may feel a great deal of guilt as she gets in touch with her old world again.