You do not need proof in politics. You just need to weather the accusations than win and it all goes away after a while. This is why most candidates withdraw. The accusations, although not proven destroy a candidates life. They would rather withdraw then fight. Moore is fighting it and it is taking a toll on the establishment, especially since he can and probably will win.
They pulled this on Trump and he told them to piss off.
Hope it works out for him. Dems are really vicious.