Why does Zaroff think Rainsford is droll and naive paragraph 17?

Zaroff believes that Rainsford is "droll and naive" because he values human life.... something Zaroff sees as old fashioned, Puritan or Victorian.

"Did not make me condone cold-blooded murder," finished Rainsford stiffly.

Laughter shook the general. "How extraordinarily droll you are!" he said. "One does not expect nowadays to find a young man of the educated class, even in America, with such a naive, and, if I may say so, mid-Victorian point of view. It's like finding a snuffbox in a limousine. Ah, well, doubtless you had Puritan ancestors. So many Americans appear to have had. I'll wager you'll forget your notions when you go hunting with me. You've a genuine new thrill in store for you, Mr. Rainsford."