The laws of some States permit the use of lethal force for other than preventing imminent death or grave bodily injury.
 But if you look at those laws, the use of lethal force is still limited.
 It may be justified to prevent an imminent forcible felony, arson, robbery, in the case of a forcible break-in of ones home or under a few other narrowly described circumstances. Those crimes are crimes in which there is a strong likelihood that the victim is in significant physical danger.
 I'm not aware of any use-of-force law that could be read as authorizing lethal force against indecent exposure.
"It is long been a principle of ours that one is no more armed because he has possession of a firearm than he is a musician because he owns a piano. There is no point in having a gun if you are not capable of using it skillfully." -- Jeff Cooper