I don't know anymore about it than what was on the web links. Given that they had to carry 100 lbs of assorted stuff, I suspect that cargo bikes would have a big advantage. It does suggest, however, that experienced (but non messenger) riders such as yourself, using normal touring type gear, could be still be very useful in a disaster scenario. The website does indicate that similar events have been held in other cities, such as Seattle. Perhaps you should look into organizing one in your town? You could include a "touring class".

I did find another link with a lot of photos of the 2013 event. Apparently one guy entered (and finished) with a cargo skateboard!