An unmoderated free-for-all is an invitation to bullies, bigots, and trolls that will further toxify social discourse — Elon Musk, the world’s richest man and poster child for narcissism, is looking to buy Twitter. Not just the 9 percent of shares he purchased last week, but the whole thing. First, because as the world’s richest man, he can do things like that, and as a gigantic asshole (which…