That's the joke.
Gun control wouldn't have done a damn thing to stop this.
It was apparently a belt fed automatic weapon. In otherwords, illegal already.
So gun control wouldn't do a thing.
In fact, if a person is planning on shooting people do you think they care about laws?
"Oh I better not shoot people with automatic weapons as it is illegal"
Gun control only takes weapons away from people not planning to commit crimes. Criminals smile as they know they are the ones with the weapons.
There have been quite a few recent events that would have been much worse if gun control were in place. They were stopped by citizens with guns.
In addition, just look at gun attacks happening in countries that do have gun control like France.
yet, even with gun control it wouldn't have done a thing here.
Banning anything doesn't work.
It just creates a black market and a criminal network. It doesn't work with guns, with drugs, with books, with movies, etc. It didn't work with alcohol prohibition.
It increases crime.