I think it depends on the child. The very young have no voice in the matter and must go with the MLCER if it is required. In that case, MO is that the child is someone that the MLCER can control, maybe force to do as they do, or control by the fear the child has that the MLCER will abandoned them, too. If the kids are older and don't agree with the MLCer, or will argue with them the MLCER might not want to have to deal with that and abandoned them, or they might try to bully the child to get their own way.
In all cases, I think it is all about the MLCER and what they want or get out of the relationship, whether it is pretending that they are a FABULOUS parent, needing to control someone, or needing someone to "like" them. I don't believe that what is best for the child enters their mind at all.