You have no way of knowing that. Removing the gun from the equation would certainly have removed the gun death from it though.
Yes I do. Starting with the fact that the story about teaching gun safety is obviously bullshit and there was a history of abuse in the household. You don't have to know shit about guns to know that pressing the gun barrel against a child and pulling the trigger is an attempt at premeditated murder.
So, now we've established that it's premeditated murder, if a gun wasn't in the equation, another weapon would be. The next most obvious choice would be a knife.
It is actually quite sad and a little bit scary how eager you are to concoct fictitious scenarios in order to remove the gun issue from this story.
It's more scary how eager you are to not use your brain before opening your mouth. There are indeed plenty of scenarios where removing guns would indeed limit or prevent damage. This wasn't one of them because of the circumstances surrounding it.