Even though Mrs. Birkbeck doesn’t seem fully on board with Dad’s parenting style, she’s trying to give him the benefit of the doubt. Suggesting that he’s trying to protect the boys by not taking them to see Mum would mean that Dad is thinking about his sons’ welfare. Given Eli’s surprise at the suggestion, he doesn’t think this is what’s going on. Eli is still, however, considering what makes men good and bad.