That's an accusation far more serious than accusing someone of cheating at online chess. But it's not impossible and I had considered the thought. Ultimately I have difficulty believing that the controlling powers of chess.com would go along with a scheme like that - they're not hard up for money.
Here's an article from earlier this year about General Atlantic buying into the company.
Alternatively, Chess.com is backing up Magnus' behavior because he is a large shareholder in Chess.com.