Stand Your Ground laws do not change the legal justifications for killing. They do not allow anyone to kill. All they do is -- by removing the legal obligation to retreat when threatened -- make it more likely that you will be in a situation where you need to use lethal force to defend yourself. But the circumstances under which such lethal force is legal authorized do not change by virtue of Stand Your Ground laws.
If you could not legally kill someone in a particular situation before SYG was enacted, you also cannot do so afterward.
An example: you're walking on the street, and someone comes right up to you with a knife and threatens you with it. Without SYG, you are legally allowed to shoot them dead. With SYG, you are also legally allowed to shoot them dead. In both cases, you are acting in self-defense from a real and imminent threat on your life.
However, if you were in your car and he were across the street on foot, without SYG, you would be required to drive away. With SYG, you would not be required to drive away. But it doesn't change the fact that you can still only kill the guy if you need to do so to save yourself from that real and imminent threat.
You can argue about the duty to retreat; my view is that if I retreat, the person might harm someone else who is less capable of defending himself than I am, and so I have a duty to my neighbors to not retreat. That right action to take should be seriously considered by each person, and they come up with their own answer that is best for themselves.
But what you cannot reasonably do is claim that SYG provides a license to kill. It doesn't. You may only kill in defense of imminent serious bodily harm to yourself or others, with or without SYG.
(Now, it may be true that some specific statutes have specific language that do modify the legal authorizations for using lethal force, but to the extent that they do, they are not SYG laws. It's like if we have a marijuana legalization law that also allowed you to use heroin, and someone said "marijuana laws allow people to use heroin." No, that's not how it works.)