This is a ludicrous reduction of the point McKenna was making. You're acting like he didn't directly address this fallacy. Go read The Invisible Landscape, listen to one of the lectures that covers this material (such as Eros and the Eschaton and / or his address to the Jung Society), and then address the whole of what he was saying.

If you don't think that human neurochemistry is astonishing, I think that's weird. But don't sit here and straw man his research; that doesn't help anyone.