whay wasn't mcbryde surprised about what appened at the marabar caves?

From the text:

"Mr. McBryde was shocked at his downfall, but no Indian ever surprised him, because he had a theory about climatic zones. The theory ran: "All unfortunate

natives are criminals at heart, for the simple reason that they live south of latitude 30. They are not to blame, they have not a dog's chance--we should be like them if we settled here." Born at Karachi, he seemed to contradict his theory, and would sometimes admit as much with a sad, "quiet smile.