I'm not aware of any states that require a person to have a permit to own a weapon. The concealed weapons permit is available in many states but not all. To the best of my knowledge, a felony convicion and mental health inquest/ajudication are immediate reasons for exclusion and most sexual abuse type offense would be felonies, but not all. Many get reduced offenses for admission of guilt and saving the Courts time and money. Of course the myth of gun control rears its head right away because crooks and hustlers don't abide by most laws to begin with. But yes, it is a tactic that could be used very well in some cases, but like you said, once all the facts were lined up.