If a user wishes to underscore that a comment he is replying to is wrong, then he should do just that. There is no need for the user to attack the person making the comment.
Calling someone "completely unfamiliar" is not much of an attack. I don't think it's any worse than saying the comment is "completely wrong", but it gets the point across slightly better.
I was being charitable here. The less charitable alternative is that the person I was responding to was familiar with the literature, but nevertheless engaged in willful deception.