A child who has not reached the age of reason and therefore is not responsible for sin is not going to be rejected from Heaven. The kid was only five. I doubt seriously what the Santa told the child would be considered by God to be mocking him. This is of course assuming the story is true.
What would you have told the child?
First of all I wouldn’t be dressed up in a Santa’s outfit. Secondly, I wouldn’t refer to heaven as pearly gates as if the child knew what that was. Thirdly, I would tell him how much he is loved by Jesus and his parents. . .no need for the elf thing. Unfortunately many adults reading the story thought it was cute and they along with Santa and Mrs. Santa don’t know the “real story” of Christmas or what awaits people after death. Come to think of it, I don’t really remember believing in Santa. A girl in my 5th grade class was still believing in him and her mother made a nasty phone call to my mother because I told the gal the truth not knowing at the time she still believed in Santa. Time on this earth is very short and unfortunately this country majors in the make-believe. Just look at the election and what or should I say who many of the electorate “believed in”.