I'm not defending pulling the dog by the tail. I'm just saying it's a separate issue from the specific claim that he shocked the dog. They are separate so it isn't topical for the shock collar discussion.
The point is that there just isn't enough evidence for the shock collar claim. Offering an alternative explanation of events doesn't meet the standard of proof. Especially when the tangible evidence we do have, like eye witness accounts and demonstration of the collar suggest a shock was likely not used.