I had the very experience I cite.  As a young boy in Holland we learned about Zwarte Piet, or Black Peter, who carried away naughty young children in his sack.  I had quite a fear of Zwarte Piet as I was a very disobedient and unruly child as all children of that era were considered to be.  
My first actual encounter with a black person was as a 5 year old seeing a black porter on the CP line as we journeyed across Canada to our new home in Alberta.  I somewhat overcome my fear given the character and humour of this individual and how he treated children like me, on the train.
Regardless of how you feel about the niqab ban, I feel this is a teaching moment.  There's a person inside that niqab who breathes and feels not a lot different from you or me, and who might also have very young children at home, just like this child, and this is what the child should be taught.  Love conquers fear, and the sooner we begin with that, the better, IMO.