You would be steel-manning his essay if you assume he’s right in these arguments. Unless you believe that no position is more correct than another or that no one is more often correct than others, you can imagine scenarios where the author is often more correct than the people he is dealing with.
Isn't that what I'm already doing? I assume that the author believes that he's right often enough to argue his position(s), but feels dejected without being proven wrong at the end of the argument.
But there's another important point here: the answer to the "am I really right?" question isn't always clear at the start of every argument.
Unless you believe there's room for (dis)proving your position, or getting some nuance on a topic [1], it's not a debate or an argument - it's a lecture. And lectures depend on other social dynamics which don't apply here.
[1] For example, maybe there are other reasons behind the position that the person can't express easily, or maybe you're actually arguing about different things.