Give homeowners the same benefit of the doubt cops get when they kill someone that threatens them. Probably more because they aren't trained to deal with immediate threats and evaluate the options like a cop would.
Asking some poor bastard whose never had an altercation and that's scared of being killed or their family being harmed to evaluate a proportional response in seconds is pretty unrealistic. And then making them go through months of legal hassle and cost to prove that what they did in that moment was correct is cruel and unreasonable.