Y'know, I didn't see anywhere in the article where the dogs owner blamed or criticized the trapper in anyway, shape or form.  I'm sure the trapper was pretty upset about finding someone's dog in his trap.
This is just an unfortunate incident, one of those things that happens.  Could have been worse.  Wolves could have gotten it, or it could have gotten hit by a car or snow go.  The dog is still alive, and despite losing a rear leg, should lead a happy, active life.  Dogs cope well with losing a back leg, a front leg not so much.