My guess is that we're going to get a law anyway, and my hope is that it will consist of small measures that might have some tiny actual effect, like restrictions on magazine capacity. I'd also like us to encourage people to gang rush shooters, rather than following their instincts to hide; if we drilled it into young people that the correct thing to do is for everyone to instantly run at the guy with the gun, these sorts of mass shootings would be less deadly, because even a guy with a very powerful weapon can be brought down by 8-12 unarmed bodies piling on him at once. Would it work? Would people do it? I have no idea; all I can say is that both these things would be more effective than banning rifles with pistol grips.
But I doubt we're going to tell people to gang rush mass shooters, because that would involve admitting that there is no mental health service or "reasonable gun control" which is going to prevent all of these attacks. Which is to say, admitting that we have no box big enough to completely contain evil.
She has no idea whether it would work, but she's certain it would work better than gun control.