Looks like you can't define it, otherwise you wouldn't have tried the spin.
No, it means that he's questioning Buchanan's assumptions. Hitler threw the word "culture" around a lot. Do you hold the same definition of "culture" as Hitler?
Everybody knows what "our culture" is...and if you have to ask, then you wouldn't understand anyway.
Folks like you remind me of Hermann Goering's dictum: "When I hear the word 'culture,' I reach for my gun."
When people are unwilling to define what they mean by "culture" on a public forum, but instead speak in tautologies, it's a sign that they're up to no good.