From the letter the teacher (?) wrote to the newspaper:
While I can appreciate the poem for its literary value, the subject matter is offensive to me, and the reading of this poem to the children imposed values upon me which are against my deeply held religious beliefs. I could not in good conscience present the notion of Santa Claus as a truth to the children, and stated so.
So there's the problem. Instead of realizing that public figures (politicians, teachers, reporters, etc) should be seen as impartial in the eyes of the public, this loon has decided to use her position of power to preach her believes to people forced to listen to her.

As a parent, I would be quite upset if some flake ruined my childrens dreams. Yes it's a fake story, but why do my kids need to face the real world at such a young age. We have long enough to see the ugly side of life, but all too short a time to truly enjoy the magic of youth. Kids will always find out the truth later in life, but I doubt they will be bitter at being lied to, but will rather enjoy the experiences of their childhood.

Sounds to me like someone got a lump of coal in her stocking as a child.