Earlier quoted context omitted.
It's not. He's directly refuting the claim made in the title of the blog post. That is: Most startup theory is ex-post, therefore bs. In the title, the author is seemingly making the claim that all ex-post startup advice is BS. The commenter is debunking that claim by providing sound ex-post advice.
> directly refuting the claim made in the title of the blog post. That is: Most [...] In the title, the author is seemingly making the claim that all [...]
(1) Most startup theory is ex-post, therefore bs.
(2) All ex-post startup theory is bullshit.
Those claims may or may not be true, but there's no contradiction between the two. The title does indeed seem to implicitly claim (2), in the form of the following (implied) syllogism:
Most startup theory is ex-post.
All ex-post startup theory is bullshit.
Therefore, most startup theory is bullshit.
Or, more concisely: most startup theory is ex-post, therefore bs.