Valid or not, the point is undermined by the author's abrasive response to counterpoint: https://twitter.com/mattgemmell/status/227818567851180032
Having your words twisted is definitely insulting.
And, whether you agree with Mr. Gemmell or the other two gentlemen, this was a misunderstanding at worst and the assertion that the "piece is really personally insulting" is laughable. (It's probable that he responded out of frustration, which is only human, but perhaps he could have used the opportunity to clarify himself.)