He did not claim the author was an idiot and dismiss his writing because of it. That would be ad hominem. He read and ingested the article and then (rightfully) drew the conclusion that the author is an idiot.
Even if one accepts his conclusion as correct, he did not explain how he came to that conclusion very well.
While I can, in fact, guess why he concluded that, I am merely guessing because his reasoning was not explained very well.
I really hope that I'm wrong in believing that about half of his problems are with the use of political labels. The very meaning of all political labels is contested: people abuse them constantly for their own purposes, so they do not carry the same meaning for all people. For example, "socialism" can be anything from an oppressive government that ruthlessly punishes success to neighbors banding together to help each other out in times of trouble. Or it can be used as a simple insult.
The problem isn't that these words have no meaning, the problem is that people are fighting over what these words should mean. As Lewis Carroll put it, 'The question is,' said Humpty Dumpty, 'which is to be master -- that's all.'
