$$,
Good points on Macca, but keep in mind that distances are often HORRIBLY wrong in triathlon, even the world championships. At the World Cup in Sydney (2000), the 10km course was over 2km short! That's a pretty big oversight.
Although I haven't scanned a list of all his race results, I'll bet it was a short course when he pulled a sub-30min 10k.
Regards,
-Clive