First off, I was taught that the human body was made in God's image. That no part of it is indecent, only the manner in how we perceive it. Yes, thus is a huge cultural difference, that being said, I would not resort to violence, or threats. I would tell my child to look away, and I would expect obedience. Then I would go up to the person and let him know his behavior was unacceptable in s public place. That I would do under any circumstance, as I live in this culture. To be fair, I do not have kids, perhaps my response would be different if I did.
I will say, I was raised not to cheat or lie, and I have done both. There have been times when one, or both, if those actions were prudent. As I have said, at least I think I did, I believe the person who did the apron thing was wrong in what he did. But, I don't see either if these two offenses as worthy if violence. Incidentally, do you believe you do more for your daughter by going to jail for assault over being thre to explain how dumb some men will behave at times?