Why? Pray tell.
Steve Irwin would certainly have wanted it shown.
That would have been his wish IMHO.
If he left a will or some other statement to that effect then his wishes should be honored. I have no reason to believe he would want his death shown all over the world. In the absence of any will or similar statement the decision rests with his heirs and it sounds like they have made up their minds. As a matter of personal opinion I think it should be destroyed. Beyond some depraved sort of voyeurism, why would anyone want to watch someone else die? It's rather like asking to be a witness at an execution. I think there is something wrong with people like that.