It's law in the US, and he is a United States Senator. Just because people in the military don't report sexual assault for being whacked in the balls doesn't mean one couldn't, or shouldn't. Sex isn't evil, but sex is often used in the workplace to coerce, intimidate and violate. There is absolutely nothing wrong with sex, there is absolutely something wrong with violating consent. People have the right to their bodily autonomy, some people even have strict religious codes that they've been working all their life to follow. Some people commit suicide after a sexual assault. If you want to hit your own balls that's fine, if someone gives you express permission to hit their balls that's also fine (though you should probably get it in writing), but if you go up and down the streets hitting people in the balls you're going to get arrested.