That is one beautiful puppy.
Not to scratch my head too much but that's a big, not heavy, dog.
The neighbor saw the carrier jerk up the dog and throw it up in the air? Something weird in the story. I could see a carrier coming into the yard and kicking, hitting or dragging the dog. Somebody looking to do something mean to a dog would not get the dogs teeth anywhere near their neck.
What a beautiful little dog. If anyone did something like that to one of my "babies", I'd do the same back to them...but worse. There is no excuse for that kind of treatment.