That's the point. They wouldn't need substantiating. Public image. It's one of the most difficult accusations to defend yourself against.
Apparently, no substantiating is needed for Trump accusations either.
It's not the governments job to silence people's freedom of speech because of this and actively hide allegations. You think they'd do that for you or me if someone accused us of being involved in some pedo-ring? We aren't rich enough for that. Why should rich people who lie down with dogs get special treatment? If you don't want to be accused of being involved in that, then don't associate with people who you know behave like that. Again, these people are so wealthy they have the whole world and as many beautiful women as they want, at the tips of their fingers. Nobody made anyone party with him.