I got confirmation from Toyota I could post this. It is for the 2011 Corolla, but nothing has changed. Refer to page 3 under 'Towing Capacity'. Walk into a Toyota dealership I am certain you can pick up the hard copy of this as it is a PDF of the brochure
http://media.toyota.ca/pr/tci/en/toyota/document/11corolla_e.pdf?ncid=13031
That's a pretty compelling document Mike, but it still does not alter the fact that the policy has apparently changed from Head Office. Toyota Canada does not want or encourage you to tow with the 2012 version of the Toyota Corolla 1.8. It is most likely the same version of the 2011 model. Legally, you would have a strong case for using the vehicle for towing based on this kind of information, if it is in fact the same vehicle.
There must be a reason why Toyota Canada is discouraging owners from suiting up their 2012 units with trailers. But, from your post it looks like it would be OK for occasional dump duties. I think your post represents a conundrum for Toyota. Changing a policy midstream looks unprofessional at best. But, I suppose they will rely on their official policy as regards warranties.
So, what is the answer? Buy a used 2011 because they are legal? Or, buy the better equipped 2012 with all the goodies ( 18,500 where I live ) knowing that is capable of 1000 pound dump trips? Based on your post one would indeed be encouraged to do the occasional towing stint with the 2012. And, damn the torpedoes.