The basis of language lies in Falsification. We naturally separate things into categories based on what qualities they don't have more than what qualities they do have. The reason we identify a Cat as a Cat and not a Dog is because they're not the same thing and the fact that they share so many qualities doesn't even come into it.
So to say that Atheism (in the modern, informal sense) is a pointless term is a massive tautology, of course it's a pointless term, in the same way that 'Cold' is a pointless term.
Cold = Lacking heat
Dry = Without fluid
Dark = Devoid of light
Atheist = Not religious
Of course, that last one doesn't quite work, because the A in Atheist is a prefix. We call people who believe in a single deity 'Monotheists' (Mono meaning 'one'), we call people who believe in many deities 'Polytheists' (Poly meaning 'Many' or 'Several'). 'Atheist', therefore, is the name of a category of people who choose not to believe in, or rather, not to worship,any Gods. 'Atheist' describes a conscious decision that a person makes, not a quality that they lack.
So what we're really dealing with is the separation of the word 'Atheist' from 'Godless', because they are very different things. 'Godless' refers to something that is 'lacking God', but God is an immaterial, esoteric, non-quantifiable, intangible thing, so things can't 'lack' God in any real sense. The point that Harris is trying to make just doesn't hold up, because he's not thinking about the root of the word.
Another problem with trying to make this sort of point is that it works in reverse. Now as amusing as it would be to group all believers under the heading of 'non-atheists', I get the impression that it wouldn't sit well with the vast majority of them. Also, 'Non-Atheist' is a double negative, and so is even more pointless than 'Atheist'.
Unfortunately there's a huge amount to say on this subject, and I'm bored of typing now.