It usually is a red flag. But not always. Some thinkers take a while to soak in, because they're rewiring one's world view rather than just making specific claims that could expressed in bullet points.
"This seems like garbage." "No, you have to read all 200 volumes of the manga. When you've read Vol. 201, you'll see why I should be the king of America, and also the king of England. Although I am American."
Paul Graham might be at the other end where you can read very little of what he writes before it starts making sense (except for the technical/programming stuff).
This piece is very easy to understand as far as what it argues, harder to understand as far as how it was actually written and published in its present form