No it's not.
Call CPS and also file in family court, that's all Brian had to do including not letting his son be at their house or near AB if she's drinking and/or ask the judge for supervised visits for her.
When it comes to the safety of a child and that child is knowingly exposed to danger a judge will give an emergency protection order for the child until an investigation is completed.
CPS will talk with Brian and his son, ask neighbors etc.
JT was on some kind of probation for violence and in anger therapy and I will assume that him NOT drinking was part of his restrictions?