But he doesn't deny entirely. Like I said, he's down with the enchanted volcano, perhaps because it might hurt Zatanna. He's against the mindwipes, because he knows they exist.
He's just not down--looks like to me--with people telling him certain things are magic as an overarching descriptor. I think he or any character would be not so smart at all to take a single weird experience--a really weird experience--or wacky story at complete face value.
It'd be like, kind of, having a near-death experience and calling it a religious experience for absolute sure. When it might be due to one's body shutting down. Different people are going to interpret something like that differently. I think he'd go with the science explanation.
I don't think he (or Clark, for that matter) would base their facts on a single test.