I've been a big fan of both Derek and Marie for over a year now. This is why as soon as I saw the comment below, I couldn't wait to see how Derek handled it -- and which I'm glad he didn't ignore.
What I liked about Derek's response is that it felt a lot like his blog articles. He has this style of laying down a situation or scenario first to connect with his audience to then follow up with helpful advice. In this case he did the same thing with his response by not taking it personal, and responded instead as a serving consultant helping answer Teodor's question.
That being said, here is a video by Marie explaining the importance of not responding right away to negative comments when you're frustrated or upset..