Cool sign and I am a believer in the maxim that a good shoot is a good shoot but if I were an attorney representing the family of a miscreant who ran afoul of a home owner with that sign on the front door and was suing the home owner for wrongful death I'd make sure the jury saw the sign and state only that they should draw their own conclusions. Even in Oklahoma I'd do that. Pre-trial I'd argue to the presiding judge - so I could get the case to trial - that Oklahoma's shield law didn't apply since the home owner was obviously gunning for anyone that unlawfully entered his home. When the judge said it wasn't obvious to him/her he'd be told, "shouldn't a jury decide that!"
Posting that sign at a home is just asking for trouble.