You haven't read the law, apparently. I have. It doesn't say "feel".
"If the person was in imminent danger of death or grave bodily harm, or believed himself to be in imminent danger of death or grave bodily harm, and if a reasonable man in the same circumstance would also believe himself to be in imminent danger of death or grave bodily harm..."
This is a necessary and ESSENTIAL provision that is in almost every state's laws. It is necessary to deal with situations where, for instance, a robber points what appears to be a real gun at you and says "your money or your life!"... and it turns out to be a fake gun after he's shot dead. Yes, this has happened. This is why the "reasonable man test" is there for "believed there to be a threat."
It would be nice if people would try to have a little knowledge about a topic before pontificating on it.