Cheering on a rape taking place in front of you does not qualify as merely being a “horn dog”.
I had never heard of that allegation and to be revealed only now 50 years or so later, seems very odd. Wouldn’t the victim have spoken out at some point? I doubt many men or women were saints, so the womanizing rumor is one thing, even though it’s gossip at this point. But an accusation like being present at a rape or the rape itself would need some sort of conviction to be considered true in the U.S. Maybe not in some countries where you are guilty until proven innocent. I don’t like it. It’s wrong. Especially after the accused is dead.