There are plenty of other ways to mass kill. As long as those who do evil walk among us, they will find a way.
This was clearly a damaged, a violent, and of relevance, a guilty young man, and as we’ve seen in similar cases, the government knew about him.
A “compiled for law enforcement purposes” deferment hardly seems necessary or reasonable with the killer dead, and suggests some other motive for not releasing requested documents.
Left unsaid is what “action” would have prevented this atrocity. That’s because none could have.