What were the criminal's motives? He found the woman and her children in an attic crawlspace. Not the most likely place to find valuables to pilfer. I believe he was searching the house for its inhabitants.
What if the woman didn’t have a gun? Judging from his mug shot, the 32 year-old criminal would have had no trouble overpowering the woman and her twin 9 year olds. He apparently had just a crowbar. But without a sufficient deterrent, the woman and her children could very easily have become rape and homicide victims — victims of "crowbar violence".
The scenario this woman and her children faced is far too common, and far too often the criminal has the upper hand when the assailed are unarmed.
Thomas Jefferson kept a journal in which he included a quote from Cesare Beccaria:
Laws that forbid the carrying of arms ... disarm only those who are neither inclined nor determined to commit crimes ... Such laws make things worse for the assaulted and better for the assailants; they serve rather to encourage than to prevent homicides, for an unarmed man may be attacked with greater confidence than an armed man [ref].
Florida State University Professor of Criminology Gary Kleck conducted a series of studies of large, nationally representative samples of crime incidents. He found that crime victims who defend themselves with guns are less likely to be injured or lose property than victims who either did not resist, or resisted without guns. Kleck's surveys also suggest that annual defensive uses of guns by crime victims probably exceed the number of crimes committed with guns [ref, ref]. A 1993 national survey conducted by Kleck and Mark Gertz found that over a five year period 0.5% of households surveyed reported someone using a gun for personal or household self defense, amounting to approximately 162,000 incidents a year [ref].
In a government-sponsored 1994 random telephone survey of 5,238 people there were 1,678 (34%) with a firearm, 6% of whom within the past year reported retrieving their firearm because of a suspected or actual intruder. In 27% of those cases (503,481 when extrapolated to the general population), an intruder was seen, and in 26% of those cases (497,646), the respondents reported using the firearm to scare away the intruder [ref].
What might have happened in those nearly 500,000 incidents if the intended victims weren't armed? How many robberies would have occurred? How many rapes? How many murders? Too many.