Gun rights aren't for stopping active mass shooting events. Gun rights are to protect yourself and you small circle of family because the police are always too far away.
Active shootings are bad for regular people to try to stop because usually those people who do, end up being killed by the policemen they finally show up. A regular guy with a gun can never be expected to rush into a school to confront a shooter.
A regular armed citizen will be charged with a crime if they stop a school shooter or any other spree shooter in a gun free zone.
This data is disingenuous because they are plotting a unicorn event with a normal event to prove that Unicorns aren't helpful. The question doesn't make sense.
I remember taking that game home from school with a floppy disk to put on the home pc.