I think you're conflating two senses of skepticism here. Contemporary talk of skepticism is usually really talk about authority; capital-s Skeptics oppose religious authority but accept either scientific consensus or the blathering of pop-science writers as authoritative, depending on whether they're angry teenagers of not; climate change skeptics accept the propaganda of the oil industry as authoritative and reject scientific consensus as liberal propaganda because they watch too much Fox News and haven't read a book since they got out of school or because they make money off the oil industry; that trend in continental philosophy that started around 1968 and ended around when Bruno Latour noticed the climate change denial kooks rejected anything useful to the capitalist class as authoritative on the grounds that knowledge can be identified with power in a much more straightforward way than most people citing the proverb usually mean. It sounds like an epistemological position, but is really a political one; the other side is wants to claim power by making a claiming to have some kind of truth, so you reject their claim to truth. If I interpret your use of "radical skepticism" correctly, it hasn't really been a thing since late antiquity, and it was more about suspending judgment than rejecting anything, the Skeptics just learned how to suspend judgment by learning how to undermine any claim; "don't worry about it, because... and on the other hand ..." at great length.
Not exactly, but sort of. One is true skepticism and one is the modern cynicism of the professional intellectual -- which is not the category climate change denial and all that fall into. Radical skepticism, in the actual sense you mention, is intoxicating but ultimately sort of nihilistic. It does not scale. Cynicism is... sort of similar. Have you seen the movie? I would say Scopes and his students are portrayed as radical skeptics in a very real sense. (They are not equivocators, I'll grant you, but they are in a state of suspended belief.) Mencken, on the other hand, is a pure cynic -- but not a denialist. He's too educated to be that. Maybe it's the difference between rejecting the truth and believing that knowing the truth won't help anyway. EDIT: I think I could use the word cynic more and the word skeptic less, but both have their place here.I think you're conflating two senses of skepticism here.