The fact of being a parent to a 5 month old has nothing to do with it. You would not let any harm come to my 21 month old neice, either. It has to do with fundamental decency. You have some, this mother had none.
You viewpoint on the matter could be because you actually value life, human life in particular.
Leftists do not. “A pig is a dog is a rat is a boy” as a philosophy will have results such as this.
Nail on the head and "fundamental decency" isn't something that can be taught to a 16 year old "mother".