gun, since the other guy (whom he was beginning to realize really was a cop) had a bead on her, so that whether she could get off a shot or not, she was sure to be shot and probably killed nevertheless.
She was so frozen in panic that she could not let go of her gun, even when the much better trained and positioned (peering around from behind a door that gave him more cover than she had) cop had her in his sights and was warning her to put the gun down or be shot.
Her gun would have done her no good with all those armed and armored invaders, but it definitely put her and her boyfriend in greater danger of being shot by them, and when she really, really needed to put the gun down to avoid being shot, she was too frozen to do so.
The only thing that saved her was her boyfriend's calm consideration of the whole picture and his willingness to raise his hands and approach the cop while speaking calmly and reasonably.
The cop, too, though supposedly better trained, was also unable to think beyond the gun.
All he could think of was to targeting the person in front of him and shout threats and obscenities. Unlike the calm and reasonable boyfriend, he could not lower his voice and speak in a nonthreatening way to deescalate and defuse the situation. Like the woman, the lead cop's entire response was embodied in the gun he held in his hand. (And his later comments strongly suggest that he goes into every police action with the same sort of unreasoning terror that the woman felt when her home was invaded by armed strangers--a clear indication that he should not be in law enforcement.)
One of the worst aspects of our present devolution into a police state is that police are apparently no longer trained or encouraged to deescalate the situation. Instead, whether because of pervasive TV and movie depictions of warrior cops, exposure to digital war games, the militarization of our police forces under the Patriot Act, roid rage, the pervasive perception of everyone who is not a cop as a less than fully human enemy, or a combination of all of these, today's cops seem unable to think of any tactic other than attacking with maximum force and ramping up the both the verbal and the physical violence, even when the police action is nothing more serious than serving a warrant or checking to see whether someone in the house might have half an ounce of weed on him for personal use.