What the fuck? He literally just listed points that refute the claim. He even cites his sources in his reply, and explains them in layman's terms.

Smugness can be appropriate if you're empirically correct and not obnoxious about pointing the correction out. At that point it's a judgement /perspective of the reader more than an intent.

The only "smug" thing about his original post is that he doesn't lead with the best rebuttal. Given the other fair points presented, that's about as deserving of smugness as you can get.

I looked at his other responses just to check if I missed something, and because I have time to kill. If you consider linking to a Wikipedia page where it describes what he has shared as "smug", I am loathe to ask what a truly condescending person would be to you.