Surely you would concede that because person A initiated a long chain of events doesn’t make him/her responsible for the ultimate outcome. Lots of things can happen during that chain to alter the outcome and therefore any culpability.
The claim is the "stand your ground' law allows you to use lethal force in self-defense, and to not be prosecuted for the killing.
AT The same time the same law creates some standards to be met first. YOU can easily lose your right to claim that law as a defense against prosecution ~ e.g. by using lethal force when there is no evidence that you feared for your life.