Mafia 99. The tragedy of the city of Ve-He.

What prevents the moderator from saying that they observed a couple of turns and came to the conclusion (based on behavior) that "that guy" might have either this role or that role?

If they can support their position with quotes from the accused player's posts that supposedly reveal them, or excerpts from the newspaper, and not just shout "I figured it out, he's Mafia, let's hang him!" Then, of course, he's Mafia, and there's no need to argue; he's either this role or that role, and there's no other possibility simply because I said so! (This is an example of a typical reveal.)