Not necessarily. What the law gives the homeowner is a presumption that the use of force was justified, but the presumption is rebuttable.
-- But does SYG mean that, if you start a fight you can't finish that you have deadly force as a backup? --
"It depends." Under Florida law, see FS 776.041 - Use of force by aggressor.
The justification described in the preceding sections of this chapter is not available to a person who:If you start a fistfight, intending to bruise your opponent, and your opponent escalates to baseball bat, samurai sword or handgun, you are allowed to defend your life.
(1) Is attempting to commit, committing, or escaping after the commission of, a forcible felony; or
(2) Initially provokes the use of force against himself or herself, unless:
(a) Such force is so great that the person reasonably believes that he or she is in imminent danger of death or great bodily harm and that he or she has exhausted every reasonable means to escape such danger other than the use of force which is likely to cause death or great bodily harm to the assailant; or
(b) In good faith, the person withdraws from physical contact with the assailant and indicates clearly to the assailant that he or she desires to withdraw and terminate the use of force, but the assailant continues or resumes the use of force.
Your examples are cogent, and I understand them.
What I don’t understand is situations that don’t exactly have an “initiator”.
Example: when I lived in Brooklyn, I used to cross the street a lot. If an armed citizen does not cross the street, and the inevitable bumping and name-calling starts, when is the threat enough to use deadly force, and does SYG imply that you were right (by the law) to walk into a situation that you knew, or should have known, would escalate?
“No duty to retreat” sounds clear, but lots of street hassles start with failure to exercise common sense and good judgement. That’s not “aggression”, but it could sometimes be “initiating”.
I understand about SYG in your home not being absolute, I was generalizing. If you kill your daughter’s boyfriend, I imagine the DA will have a few questions. If you kill three armed Amish at zero dark thirty, not so much.