Carlsen was making mistakes. That wasn't his best game at all. Are we sure we aren't talking of this because someone's ego was hurt?
> And after the game he was unable to explain his own ideas, proposed ideas that were simply losing,
That doesn't mean anything at all
> referenced games that did not exist,
That did exist close enough to the period he mentioned. Remembering the position and analysis is necessary, remembering when exactly this position happened and even between whom exactly is utterly useless.
> and was generally (relative to the class of player here) clueless.
He didn't make a clueless impression to me. But I'm not Carlsen's fanboy whos accusations can cloud my own reasoning. If I was, I'd probably believe that Niemann is a proven cheater and would look for facts to confirm that bias.