It would be unjust on any dog to leave it without the surety of adult supervision in the presence of young humans – young humans learn by trying things and they don’t always know that punching, pulling, etc aren’t really liked by anyone, least of all a dog. A dog’s immediate ‘defense’ is to go away (hide somewhere) if they can’t do that, it is only logical they will treat the ‘abuse’ in like kind and can bite – Clumbers aren’t noted for biting, but provoked properly I assume they will bite.