It is relevant because Biden doesn't say it's okay to shoot at the person with a shotgun at the front door.
Here's the full quote:
Well, the way in which we measure it is -- I think most scholars would say -- is that as long as you have a weapon sufficient to be able to provide your self-defense. I did one of these town-hall meetings on the Internet and one guy said, "Well, what happens when the end days come? What happens when there's the earthquake? I live in California, and I have to protect myself."
I said, "Well, you know, my shotgun will do better for you than your AR-15, because [if] you want to keep someone away from your house, just fire the shotgun through the door." Most people can handle a shotgun a hell of a lot better than they can a semiautomatic weapon in terms of both their aim and in terms of their ability to deter people coming. We can argue whether that's true or not, but it is no argument that, for example, a shotgun could do the same job of protecting you. Now, granted, you can come back and say, "Well, a machine gun could do a better job of protecting me." No one's arguing we should make machine guns legal.
He was talking about the effectiveness of shotguns compared to AR-15s. Also he had a point about the machine guns.
Do you really need an AR-15 for self-defense when a shotgun would be sufficient at warding away people in the "end days"? Besides, if people get the wind that you have an AR-15 or more, they'll do anything to get to them.
Ever seen a zombie movie? Okay then you get the idea.
Jesus you people would do anything to paint anyone you don't like in a bad light.