If you get caught cheating, even once, you should be banned for life.
Otherwise we end up in a lose-lose situation.
It’s almost impossible for Magnus to prove Niemann cheated on that game.
It’s impossible for Niemann to prove he didn’t cheat.
But shouldn’t matter. He was caught cheating before, he shouldn’t have been allowed to compete again.
I don’t remember Ben Johnson or Lance Armstrong getting a pass
Edit: Replies seem to focus on my examples. Forget about them. Proposition stands. If you are old enough to compete you are old enough to be banned for life if you cheat. Online or OTB.