Yeah, I think Matt is going against the tide here, and making it much more difficult than it needs to be for practical purposes. Hitchen's usage makes more intuitive sense and IS the accepted usage, since Matt's use is making a distinction without much of a difference based on semantics. Either way you cut it, both Matt's use of the anti-theist and the 'hard atheist' would bear the burden of proof.
I suspect Matt's point reflects his theological background and training, since he also says that 'knowledge is a subset of beliefs' (which is the theological usage) which drives me crazy, whereas I'd assert that 'beliefs are a subset of knowledge' (based on the models of cognitive thought used in science, from current models used in fields like psychology). I've contacted him about it, but he cites the use in philosophy/theology as his defense for continued use, but I'd say why continue to use a distinction which is known to be wrong and worthless?
Adam