Jack, it seems, didn't take too well to being called a 'Massacre Chaser' (which, it turns out, might have been a prophetic term) and issued a public challenge to Jason to a debate about whether or not not videogames truly teach children to kill.
Jason 'took the bait' as it were, in that he contacted Jack to find out more about how such a debate would work. The entire email exchange between Jason and Jack is posted unedited here and I think you'll find it extremely informative and well worth the read.
In short, Jack's interest in the idea of a debate seems intrinsicly tied to his expenses for the trip being paid and the ~$3000 speaking fee he would expect to take away. When asked if he would do the debate for free, he responded:
I expect to see news of this exchange spread quickly around the gaming industry as it gives us all one more feather of hatred to stick in our collective cap of Jack.
That isn’t how it works and I can’t justify leaving my family to go to Montreal on a freebie. Sorry. Have to pay the bills.