A stranger slaps a toddler in a shop, arrested

Suppose you are the mother of a bonny toddler, and life is hectic for you. You need to handle the child as well as make sure that your house is running fine. So you may need to run around, do shopping while carrying your baby. However, children do not follow the rules that adults have; they can cry whenever something is disturbing, they can seem like an inconvenience to other people and so on. However, nothing can justify what this apparent stranger did when he got irritated by the behavior of this child (link to article):

A Georgia man allegedly slapped a toddler at a Walmart store because she wouldn't stop crying, authorities said. Roger Stephens, 61, was arrested Monday and charged with first-degree cruelty to children. An incident report obtained from police in Gwinnett County indicated Stephens did not know the 2-year-old girl he stands accused of hitting.
The mother said a stranger later identified as Stephens approached them and said, "If you don't shut the baby up, I will shut her up for you." A few moments later, while the mother and the crying child were in another aisle, Stephens allegedly grabbed the girl and slapped her across the face.

Now, he has been charged with cruelty to children, and one would think that it is perfectly justified that he has been charged with such a crime.