These people have the gravest mis-knowledge of “Stand your Ground” and “Castle Doctrine”.
Neither allows anyone to shoot another human being. There is NO LAW that allows someone to shoot another person.
The difference is that the person who is viewed as acting in self defense will be free until their court date. Their court date they will have to defend their killing of another human being just like a criminal.
I opened eyes with this statement a long time ago on Facebook (when I was a fool and still a member there). If someone breaks into your house without Castle Doctrine, you as the defending homeowner will have your guns taken from you, and very likely spend a night in jail. You may even need to post an expensive bond to be free until your court date. With Castle Doctrine you still have a court date to defend your actions, but in the meantime you will not be in jail and you will not have your weapons taken from you.
Stand your Ground extends the decision to outside of the home with a few exceptions. First of all, the murder weapon WILL be taken into evidence. That’s going to happen. And if you use something exotic like a flintlock pistol or a DE 50 cal or an AR pistol you will have to answer a LOT more questions. You by yourself will be allowed to go home after filing a statement and awaiting your court trial.
Neither of these laws “allow someone to kill someone”. It just adjusts you jailtime accordingly.
The Castle Doctrine and Stand Your Ground are both principles related to having a duty to retreat before using force.
In some jurisdictions you have a duty to retreat from a threat, if it's safely possible, before using force against the threat.
With the Castle Doctrine, any duty to retreat you have ends in your home. You don't have to retreat from your own home.
Stand Your Ground takes that idea and expands to any place you have a right to be.
Neither justifies the use of force on their own. There are other elements involved than just the duty to retreat. And neither has anything to do with taking your weapons or reducing your jail time.