Who's saying a single harassment complaint would automatically result in someone being ejected from a convention? That's a bit disingenuous isn't it? The consequences for the vast majority of harassment complaints are exactly the same as a single noise complaint - the manager comes, tells the person to stop doing whatever is causing the complaint and, assuming no further complaints, that's the end of the story.
Someone telling dick jokes, playing out rape scenarios, leering, jeering, and various other forms of harassment are best handled in exactly the same way. Which is the point of this entire thread - that no one is stepping up and acting. Complaints are being ignored. Complaints are being treated like some sort of bizarre role play scenario where the managers should act like CSI investigators. Complaints are being treated as always suspect because they might be weaponised against some poor schmuck.
It's questionable whether any of those things are harassment even if they were recorded.
You can't say that someone else's choice of words, body language, or taste in humor, is a personal attack just because it could be or you find it offensive no matter what. Offense is not the same thing as harassment.