Court room scene (possible spolier) sexist assumption

As she was taking her maiden name it sounds as if this was the final divorce hearing. Why then would the judge be so nasty to the father because he had the "chutpah" to want custody. He has as much right to custody as she does (it is only later he would have an obligation to show a change)

We do know she is so negligent that he mom has to call the son to tell him to put her cigarette out while she is sleeping.

She is so negligent she is in such a deep sleep, at an early enough hour that an ice cream truck is driving around, that her son can't wake her.

She now has a DCS case against her.

She left her son alone in a car allowing the two of them to get kidnapped.

Her husband may have many faults and possibly even enough faults to give her custody, but for the judge to act like it was a slam dunk annoyed me as if a mother automatically gets custody.