Not a slap in the face at all. There will always be tracks that have been around longer than whatever track they decided to host the race at.
Thornhill won the bid for a reason, they have put the time, effort, and money in the facility to be one of the best in the US. It's the largest track in North America. ROAR would be crazy to not host a major race here.
I'd bet it won't be too long before Thornhill host the Worlds.
On top of that, it's a central location. East coasters don't have to travel all the way to California to race.
Can't wait, I get to run one of the biggest races of the year and sleep in my own bed. That's never happened before.