Given that his site focuses almost exclusively on news for the early-adopter Apple enthusiast, I would guess that he would naturally have a much lower proportion of IE users in his audience than other sites, even if his site worked flawlessly in IE.

Note, for example, that he tests his site against both Safari and Firefox, so we can assume he is not turning away those users. If his site attracted the "average" web surfer, one would expect roughly three times as many Firefox users as Safari users. But he actually attracting twice as many Safari users as Firefox. Since his non-IE traffic is so heavily skewed to Safari, it's not unimaginable that his IE traffic would be similarly skewed, regardless of any IE rendering problems.