"Begging the question" does not mean inviting a particular question. It means asserting the statement that is to be proven, beginning with an assumption of your particular side of the issue to be decided.
Asides from that, he's perfectly right. The question "is the country conservative or liberal" is profoundly un-useful without a specific sense of what those terms mean. The center shifts, and very often, it shifts to the left. Which is why I don't particularly care how many people still self-identify as conservative or moderate. What was once liberal, in many cases, is now squarely centrist.