That's very interesting to read - I have the same trait and surely it must be fairly widespread and not particular to us. Essentially a trait to subject highly favoured, especially very trivial hypotheses to burdensome checking, for the sake of intellectual integrity or 'epistemic hygiene' which you intriguingly coin. Maybe this trait is called OCD.

For example, in the post above: it is referenced that the woman suggests magic exists because science does not know everything, it is replied that lack of knowledge does not imply non-existence, and the woman is said to have 'clicked' by concluding that magic is inconsistent. While this final conclusion sounds very reasonable, for completeness I still felt the need to question: "inconsistent with what?"

First let's lay out the reasonable premise: 1. I think the unspoken implied principle here here is that magic is defined to be what is unknown.

So we can test the consistency of this principle. If one person does not know something, and the other person does, then regarding this something, magic would have to exist for one but not exist for the other, respectively. Therefore there is a logical inconsistency in this principle (unless we accept solipsism, but then we would have difficulty talking about real 'other people', would we?)

However, I do suppose that if only one person existed, there would be no other person to create a logical inconsistency and in a strict sense magic would be consistent. It would merely constantly change based on your epistemological state, and you would probably need Occam's Razor to dispense with it.