Strawmanning the education systems by ranting about tree-hugging hippies who indoctrinate the children and calling taxation theft isn't critical thinking, it's living in the bizarro world that is modern American conservatism.

His views also aren't non-conformist at all, they have a deep history in US politics. Friedman, Hayek, and so on for a large time during Sowells career practically dominated public discourse. Friedman alone probably is the single most influential economist of the last few decades as far as public discourse is concerned.

And that is squarely where Sowell is situated given that he hasn't ever actually worked as an economist, but basically as a pundit. Within American conservative punditry his views are as standard as it gets.