> This is like the textbook definition of an ad hominem.

No, it isn't at all. Ad hominem is only in effect and fallacious when the logic turns on the personal attack. "You're wrong because you're stupid" is ad hominem. "You're wrong and also you're stupid" is impolite, but logically fine.

To clarify, I think that the entire "History" section is unrelated to Andrew's argument, only the "Addressing the Blog Post" section actually contains arguments, and that section doesn't contain the rude comments, it's focused on technical decision-making.