He has been caught of cheating online. Where you just open a new window and follow engine moves. Or you have a friend sitting beside you giving engine moves.
In his over-the-board match, he didn't have a laptop. He didn't have a friend giving him moves. He didn't have any communication device. He was mostly looking at the board or into the distance while he was playing. He was scanned with a metal detector. So we know he definitely didn't use any of his earlier methods of cheating if he even did cheat. Carlsen's statement confirms that his preparation wasn't leaked or hacked. I count these as evidence of him not cheating with his usual MO.
But in your analogy, it's completely possible for the guy to have used his usual MO to steal the new shiny car.
Now of course I'm not saying he didn't cheat. It's possible he used some other sophisticated method of cheating. But it would not be natural for a reasonable person to assume that theft using his usual MO is the most likely explanation.
That's not a complete analogy tho. Everyone knows Hans cheated in the past. But Magnus is going beyond that and saying that Hans cheated in the over-the-board game against him.
Coming back to your analogy. So now imagine this person suddenly has a new shiny car but he also has the Title and registration for that car. Not only that, someone reported him to the cops and the cops said that the car is not stolen. He also has income tax returns that show that he has a legit source of income. Would it be natural for a reasonable person to assume that theft is the most likely explanation?
I would love to give this a try if it has an MIT license.