It's also a religious thing, not trying to say anything bad about religion at all, But the reason guns are okay but Boobs are taboo is because of how nudity is seen as immoral and sinful. nudity over here seems to be worse than so many things.
On TV you can show violent movies where people kill each other all the time, they can even show some gory stuff, but anything naked and the channel will have to pay a fine and issue an apology. so you can have someone cut the head of another person in a movie and no one really minds, but if they show a nude woman they will have to apologize to everyone for it