It is prob a real bear but not that big. Look at the ground around the paws of the bear, I see boot prints and leaves on the ground that IMO make this bear look small to average. Looks like just another long arm or photo shop pic too me....
It was definitely having a bad hair day, and it's claws look too short unless it's been spending a lot of time on rocky ground. Griz tend to walk with their claws off the ground most of the time and the claws are normally much longer. At least that's what I've observed when watching film of them; no personal contact.
A decent wide angle lens will make everything look much bigger and still keep it in focus. Big Luke got it right when he noticed the boot tracks and leaves in the foreground! By looking at the grass and brush it looks like it's fall and I suspect that's why his claws are stubby because he's been digging all summer and wearing them down.