Yeah, this is probably it. They didn't hold it for the past 2 years.
UT, the Catapults, trebuchet, and centrifugal are more dangerous. This is the first time I've heard of an incident with an air cannon, but I've seen a pumpkin go backwards from one of the other machines on more than 1 occasion.
I wasn't there this year - they changed the rules about where you can party. It would have been $300 to park in the VIP tailgating section on Saturday, and that's the only place you can loiter and drink.