I have worked with many children in my life as a babysitter/nanny. Little kids lash out for all kinds of reasons, and even though that mom was in the process of comforting her child, I am sure she understood that to some degree. I am glad that you decided you would still take him to McDonald's. Like you said all kids are always learning something. They are all learning communication skills. It might look different for each child, but no one can deny each one has to learn in some way.
Thanks for sharing, Scot!