If the enemy has breached the defenses of, say, Fort Gordon, GA where you are employed as a hacker/contractor, then the massive damage has already happened and the M16 (which wasn't assigned to the hacker anyway) isn't going to change the result.
By that logic, the marginal extra gun in Fallujah shouldn't have stopped the Coalition forces. I get why you're saying that, but the military simply shouldn't operate that way. If their goal is the security of a country, then every soldier should be at least able to shoot a gun. We're not talking about requiring their PT scores to be insane, or their grooming to be on point. But shooting a gun? Really? That's a trivial requirement.