Earlier quoted context omitted.
The author has presented an argument. Whether the author himself generates any code at all has absolutely no effect on the validity of his arguments.
Since when is credibility not a thing?
See here: http://plover.net/~bonds/adhominem.html
Example:
A: "All rodents are mammals, but a weasel isn't a rodent, so it can't be a mammal." B: "I'm sorry, but I'd prefer to trust the opinion of a trained zoologist on this one." B's argument is ad hominem: he is attempting to counter A not by addressing his argument, but by casting doubt on A's credentials. Note that B is polite and not at all insulting.