Thanks for the kind advice. For me, blogging is a conversational medium, I try to write blog posts the way I would speak, and so it's pretty unfiltered. Also I try to be engaging. And insofar as my opinion/analysis has any value, I think it's better for those concerned that it be unvarnished. I don't believe most things should be sugarcoated, and I don't think the kind of people who do startups do either.
His advice might help the way you speak too. Courtesy is not sugarcoating. He noticed some good engineering in your writing, but if you want to reach people maybe your words need better design.