Yes, I have heard of parental alienation. There is no indication that occurred in this case. To my recollection, there is no indication he was unaware she existed for the first 7 years. Actually, no one has said any reason whatsoever why the father was not involved. All they did say was he was not involved in the first 7 years. Speculating beyond that is pointless.
What we do know is by his own words he decided "he has had to separate himself from Steppe and his daughter because of this incident. “I can’t ever have a relationship with them again,” he said."
https://www.yahoo.com/parenting/dad-arrested-for-taking-daughters-phone-as-171354368.html . Not a history of issues. Not a list of issues. Not because mom is alienating me. He merely listed this one issue as the reason he no longer wishes to be her father.
She is a child. She does not get to decide if a parent is in her life or not. Very few children would have any parents in their lives if it was left up to tweens/teens to decide. If your child stated they wanted to live on their own or for you to stop being their parent, is that their choice at 12 or at 15?
Why should he pursue a relationship with his own child? Seriously? You have no idea why a father is needed in a child's life? Here is a good start for that research for you:
https://www.google.com/?gws_rd=ssl#newwindow=1&q=Research+on+the+importance+of+a+father+in+children's+lives
Maybe I forgot, or maybe I missed it, but where did it state that step father wanted to adopt this 15 year old child? I really hope someone steps up and helps her recover from this injury her father has caused.