What tone? He said you should read something before arriving at conclusions about it. He didn't add "you moron" to the end of it. And, it turned out, you hadn't read it.
Every criticism stings. They sting me even when I'm confident that I'm right, and even though a Markov 'tptacek could probably get 1000 karma points pretty quickly on HN. Don't confuse the sting of a critical comment with a breach of etiquette.