Don't all snowblowers have a safety clutch handle? Mine does. If you release the handle for any reason it automatically disengages the clutch removing power from the auger. I can't see any benefit to overriding it and it would be a difficult reach to stretch arms from the handle to the auger.

I wonder if the dog was reacting to the noise of the snowblower. I wonder what would have happened if the snowblower had been used as a defensive weapon against the dog?

Condolences to the victim though. That's a nasty wound.