Sorry, I disagree with this guy, at least as defined in America.
To be a liberal in America, your politics have to be somewhere in the vicinity of Josef Stalin and Adolf Hitler as far as desire to control. Related: There is no such thing as an effective "Blue Dog" democrat anymore, whom I never really categorized as "liberal" in the first place.
The current definition is this: If you are a powerful Democrat, you are a socialist who has more in common with the Communist Manufesto than the Constitution; certainly the IRS has proven this point already. Therefore, Democrat = Liberal = Progressive = Socialist = Anti-traditional American.
Now, in Britain whose "conservatives" are to the left of Max Baucus, a "Liberal" may seem like a "reasonable" person, but in the US, Josef Stalin would be hammered from the Left in any primary he would run in.