We have a similar icon in our home, and I used it to explain the legend to my son. One thing my wife and I agreed on, was that our son would not be taught that there was a literal "Santa Claus", rather, he was taught the story of St Nicholas, and that the popular story is just a lame Protestant appropriation of a saint. I've debunked similar Protestant errors and omissions about Hallowe'en and Thanksgiving to him, as well as to explain that, no, we do not go to Mass on January 1st because it's New Year's Day, the reason is quite different.
Children in Poland (and our son is a Polish citizen,
niestety, he hardly knows ten words of Polish, we haven't been successful in teaching him) aren't taught that there is a literal Santa Claus. We chose to follow the Polish custom instead of the American one.