Taking a shot at understanding gun lovers

I'm going to ask a question here, respectfully, and I would like some respectful answers.

You read in the paper how a guy who was beating on a woman shot the first police who arrived on the scene, only to be shot dead by other cops who arrived and could not get him to surrender.

You read how some dude, upset because his wife left him for dude #2, entered #2's workplace and shot him to death, then ran outside and shot himself.

Now, Second Amendment fans, how do either of these deceased individuals, who were alive Friday at noon and didn't live until suppertime, fall into your description of militia members, defending their homestead against redcoats or other depredation?

I just need someone to explain to me why these people should have been allowed to walk around carrying guns. One at a time, please.