He isn't right at all, of course they can't get them all, but that's just saying well it's too big of a task, so let's do nothing. Millions of guns could be taken off the streets. Ammunition could not be bought to use the guns anymore. Over time there would be less and less bullets to use. This is a major problem that requires major changes. It requires a massive undertaking. But to say it's too big to do anything about is saying, sorry about your luck to all the future massive killings.
We will never stop all murders, or rape, but does that mean we don't have laws against them? Does that mean we don't try to stop or prevent them?