I can't help but wonder just why you object to employing a tactic (under certain circumstances of course) which could possibly end the attack and eliminate the need to kill someone?
I for one would not downgrade a tactic likely to prevent a death, but you assume that the almighty racking sound would automatically de-escalate the situation without violence. There is too much of a chance for things to go wrong and end up dead as it is, why add more by intentionally adding a nonsense chance for mechanical failure to "hollywood" someone? What if the intruder was only intent on robbery, and now he knows you have a loaded gun, and will now try his hardest to kill you before you kill him? What if your hollywood shotgun rack does cause a mechanical malfunction? Why add another element of risk to a scenario, no matter how negligible you feel it is?