[Chris2048]

You could argue that sock-puppeting defeats/is an antidote to Argumentum ad populum, and is as such a valid tactic.

In this case also, it would be seen as arrogant to tell someone they aren't smart enough to understand your argument, but not so with a third party, i.e. maybe it's appropriate for playing devils advocate informally.

That said, he was also antagonizing if using "idiot", rather than being more polite himself. If he spoke through his own handle, he might have cared more about civility.