I don’t think that argument is even valid. After all, I have the option of putting a human in a box. If I do, one hypothesis states that the human will be tortured and then killed. The other hypothesis states that the human will “vanish”; it’s not precisely clear what “vanish” means here, but I’m going to assume that since this state is supposed to be identical in my experience to the state in the first hypothesis, the human will no longer exist. (Alternative explanations, such as the human being transported to another universe which I can never reach, are even more outlandish.)
In either case, I am permanently removing a human from our society. On that basis alone, in the absence of more specific information, I choose not to take this option.
I think you will have to come up with a scenario where ‘the action coupled with the more complicated explanation’ is more attractive than both ‘the action with the simpler explanation’ and ‘no action’ in order to make this argument.
My folks raised us in borderline-fundamentalist Christianity, which made the Santa myth nearly as much of a non-starter as I expect it was for those commenters who were raised Orthodox Jewish.
If and when I have children of my own, I intend to use the Santa myth as an exercise in invisible-dragon baiting, nothing more.