I guess I just felt that way after reading the anecdote of developers writing their own PDF parser, and then giving up and purchasing yours. Though I'm sure it is evidence directly from your experience, it just feels a little salesman-ish to me :)
I think the article could be stronger with a few more thoughtful paragraphs on your thoughts, and maybe removing the link (though keeping the name) to your product?
That they purchased his product makes sense, because that's how he heard about it. His product acts like a funnel for such stories.
However, I agree it's a little too conveniently self-serving. Although an appealingly elegant coincidence, it's important to not only be neutral, but also to appear to be neutral.
I think the article could be stronger with a few more thoughtful paragraphs on your thoughts, and maybe removing the link (though keeping the name) to your product?