This is way too much accusation without any evidence, and a terrible blow to Carlsen's sterling reputation. What he should have said was:
"Niemann is an admitted chess cheater, and has cheated even more than he has admitted to, per Chess.com's recent statement. Cheating destroys the game and I refuse to play against known cheaters. I will not play Hans Niemann or any other known cheaters."
"Niemann is an admitted chess cheater, and has cheated even more than he has admitted to, per Chess.com's recent statement. Cheating destroys the game and I refuse to play against known cheaters. I will not play Hans Niemann or any other known cheaters."