I have always found it odd that we teach our children to NOT lie, then fill their heads with lies of tooth fairies, easter bunnies, elves and Satan claws, er, Santa Clause. I do not know the age of your child but I will assume that they are ticked off about discovering that somebody lied to them and being "uncivil" to Santa may be an expression of this betrayal. They may not even understand their "hard" feelings toward Santa, however they will convey their feelings, usually targeting the object or the subject of any perceived or real betrayal. I doubt that most shopping mall Santa's are aware of the two part meaning of who they are and what they represent to kids. I doubt that many parents understand that these little betrayals or discovery of lies by our children can have a huge impact on how they treat the parent and others. Especially if they find out the "truth" via school mates or peers who never break the news gently. There is the story that ends "Yes Virgina, there is a Santa." in which the author attempts to express the special aspect of Santa, however adult may understand these things, children are not as sophisticated and can not fully grasp what the spirit of Santa is all about. http://www.nanaellen.com/village/cmas/cmas-virginia.htm is the story/letter. What you need to do is read this and explain this to your child and attempt to convey to them the wider significants of who Santa is and what he represents. As for the nice Santa, tell him the truth, that your child has discovered that Santa isn't real as in north pole real and has yet to come to understand the spirit behind Santa. I think the nice Santa has already been confronted by many kids who have made that recent discovery, it happens every year and many children to do not take it well.