I assume you are responding to me. Yes, yes it is. From Wiki "Argumentum ad hominem, is an argument made personally against an opponent instead of against their argument." AlexeyBrin is implying that because greenyoda may not have written any programming books, that his argument is less valid. AlexeyBrin's argument is not refuting greenyoda's central point, that it's somewhat strange that the blog post author has written a programming book about Ruby, despite not being aware of what some argue are the language's commonly used features.