I don't think it makes him an imbecile to not believe every crazy story about every artifact. I'd think he was an imbecile if he did take everything at face value. Same for every character, in any media. They're just going to accept some wild rumor? I mean, even if bizarre things exist, they ought to stand up to the scientific method, with repeatable results before everybody calls it a true deal. And if they don't stand up to tests, why depend on it?
And he DID go down in a volcano. That's freaky. Could freak lesser persons out. All that sulpher and molten lava.