Ironically, that wasn't an "ad hominem attack", it was just a plain ol' fashioned insult, which doesn't require a fancypants-sounding Latin label. But, you dismissing Gruber as an "Apple fanboy journalist" is a bit ad-hom.
Or, it would be, if this were a formal debate. Which it isn't.
Calling him an "Apple fanboy journalist" isn't an ad hominem attack unless you use that characterization to dismiss something he said. It's just an attack, and a pretty accurate one at that, if you follow his blog.
But this is totally unrelated to the immature behavior that he's showing about this whole Markdown drama.
I wasn't calling JG that, I was calling all those around him in the Apple tech press who also piled on with the insults like "jackass".
The point is that one side is name-calling and insulting the other, while the other side is trying to advance a technology for a large number of devs and internet users.
I'm just a commenter on HN with little skin in the game, how I conduct myself matters little in this debate. How the primary parties in this story act is important and revealing.
And for all their screaming, there has been barely an acknowledgement of the change. Quick to insult, a lot slower when it comes to acknowledging compromise.
Or, it would be, if this were a formal debate. Which it isn't.