Hi Rob,
Keep in mind that this is also an opportunity for them to get access to (and ownership) of a range of images for their own use.
Note in the rules -
"If Canon USA opts to use the winning photo, Grand Prize winner will NOT receive any additional compensation in conjunction with such use."
If you compare the cost of the prizes (to Canon) against the cost of having a professional portfolio done, in business terms this is a cost-effective approach for Canon.
Sorry to have to shine some cold reality on this. Of course if you want to enter go ahead, but if you think your photos are actually worth something then this may not be for you.
Ron
ronaldcraig.com