You can't prove 100% that Santa doesn't exist either, yet it still violates rational principles to believe he exists.
It violate principles because there is certain thing that are impossible in Santa definition. Flying with reinder faster than light to cover the world? Give gifts to every kids, yet, no kid ever got any gifts from him...etc Then there is the fact that Santa is a fictional character, and is not an attempt to explain anything. If you define santa has "Saint Nicholas", or a fat guy wearing a red outfit, then Santa doesn't violate rational principles since both exist.
If you want to explain a phenomenon using Santa, please do so, and it will be a valid answers if your definition actually allow you to do something. However, I'm certain we could make the demonstration that most of Santa's traits aren't useful to explain that phenomenon, and you would be left with a concept of Santa that is stripped of everything that made him Santa. Explains electricity with Santa, and you will be left with an electron named santa.