Should the homeowner take the responsibility to consider any circumstance that might come up surrounding the safety of their home? Yes. Even if this happened to you, tonight, and you killed somebody that didn't deserve to be killed.. they'd be intruding on your property unlawfully, yes, but it'd be your own dumb fault for not considering the circumstances after having a conversation like this. You'd be safe, sure, but I don't believe you wouldn't have regrets about how you handled the situation, particularly after having a good chance to think about it.
I like how I'm the center of negative attention for being the first person to bring up the fact that you should consider every possible circumstance to a situation that involves life and death. Seems a little ironic, but that's the internet for you, I guess.