Oh yes, the lengthy and expensive custody battle made it pretty clear he wanted a turn at full-time parenting.
If he tried to take it back to court now, the mom would most likely bring her psych in to testify that such a "dramatic" change would be too destabilizing for her. Plus, she's old enough that the judge would ask for her input--he doesn't have to do what she says, necessarily, but it does factor in--and we think she would probably say she wanted to stay with her mom, to avoid hurting her mom's feelings.
Our hope right now is that she can manage to weather the next two years, and then get the hell out of that household (which is emotionally unhealthy in a number of ways,) at which point she can take control of her life and hopefully blossom.