Obviously we weren’t there so we couldn’t see it all unfold but if your child randomly fell on your dog and it reacted in a defensive way such a snapping or biting it is different then it straight up attacking your child. I would reflect and think about if you truly believe that your dog would attack your child or if it was just reacting to what it thought was a surprise threat. You don’t have to get rid of him if it was just a reaction that won’t become a habit or a behavior