I'm sorry, but I feel like you're making a lot of assumptions there. We don't know that Ryan's parents actually take care of Bentley - that's what Maci has said. We don't know that his girlfriend takes better care of him than Ryan - that's an assumption. Ryan's been negative with Maci, but Maci's been just as negative with Ryan. And, I like Maci, but I don't know that I'd be comfortable if she were the main caregiver of my child right now. She seems to be most concerned with having a man.
I refuse to judge these people solely on how they behaved in the past and not take the present, and their growth, into account.
All too often, it seems like when a father attempts to get more parental rights, we assume he's just doing it to hurt the mother. I think that happened with Ryan last season - how dare he want more time with his child? And this season, how dare he care who is around his child, if Maci thinks it's okay, why is it his business?
The facts are, we see him being very involved with Bentley now. Bentley seems equally happy and comfortable with both of his parents - and yes, small children can and will show when something's not right. Consider Leah, and how anxious she gets, visibly, when her parents argue, when Gary leaves and she's left with Amber.