From a company's view there may have been specific reasons they were the title sponsor at Columbus as opposed to other locations. It may have been in a region that met what ever specific targets they were trying to reach. You have to keep in mind Columbus is right in the middle of Ohio, which probably pulled pretty decent numbers from southern Indiana, Kentucky and West Virginia markets. Now that the venue will be 2 hours further north, they may be anticipating a potential loss in reach from those markets. At the very least there will be some change in the demographic, which may not fall in line with their expectations/goals from when they first signed on as the title sponsor.
Regardless, it's insane that the NHRA didn't at least consult with them first, even if they were hell bent on making the change. I still find it hard to believe that they wouldn't have. Pontiac being the customer, you at least make them feel important enough to discuss the matter with them and let them air their support or lack there of regarding the change. It may just be a case where the move really is not a big deal for Pontiac, but since they were not at least advised of it, they felt their place in the sport was insignificant, and therefore why should they put their money into it, especially when they are so strapped?