Isn't it a joke? Not a very funny one, I have to say, but a joke. Person A posts something to LW that doesn't seem to have much relevance to LW. So person B replies with something comically-stereotypically LW that doesn't have much relevance to what A posted. There's a certain symmetry about it, and its irrelevance is also a way of saying "this doesn't belong here and so shouldn't be taken seriously". So I guess it's both a joke and a criticism.