I wouldn't call that abrasive. The "counterpoint" was quoting a previous article of his out of context, acting as if he was saying it was OK to steal content - which he was not, he was explaining WHY people steal content.

Having your words twisted is definitely insulting.

Twisted implies malicious intent, which the other individuals clearly did not have.

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.)