You do a good job of pointing out why “conservative” is as much of a misnomer as “liberal”. These days, “liberals” want more of the status quo and/or more government, while “conservatives” want radical change.
Sowell is a “libertarian” in the sense of the word as applied to the men by which he was influenced. Hayek wrote Why I Am Not a Conservative, and Friedman wrote The Tyranny of the Status Quo, for example. Sowell is probably a classical liberal (like Adam Smith) more than anything else, but to say that these days would create even more confusion. As the term relates to people like Sowell, “classical liberal” has been replaced in modern parlance by “libertarian”, mostly due to the progressive movement’s corruption of “liberal”. “Libertarian” in this sense, with the small “l”, is distinct from Libertarian Party, and I feel a little bit awkward even having to say that in a discussion with what I take to be an intelligent person. Forgive me if that was pedantic.
I am far more comfortable with Sowell the classical liberal than I am with Sowell the libertarian.