I have mixed emotions on this one, I have to tell you. Mostly that is because from the limited story, I know next to nothing about the situation.
Yes, if someone tries to get my gun from me, they pose a fatal threat and appropriate response is warranted.
On the other hand, was this security guard perhaps on a power trip or otherwise threatening excessive force BECAUSE he was armed? I think most here would agree that their firearm is a tool of last resort, and despite the fact that there is no duty to retreat, no one who is armed should ever enter into a situation they would not enter into unarmed.
If the resident attacked an armed man simply asking for the music level to be reduced, he was either completely out of his mind, or he had a reasonable fear of his own safety because of something else that came out of the encounter.
Not trying to jump to conclusions here. It was likely a justified shoot. God knows I'd rather have an armed security patrolling my neighborhood than one equipped only with a cell phone and a flashlight. Just food for thought.