Also cheating in online chess is a very low barrier if entry. Anyone can do it. When I did cheat in counter strike, it was as simple as wanting to see how it worked. Downloading some questionable binaries and running them.
A simile might be downloading an illegal copy of windows and stealing a car. Both are technically stealing, but stealing windows is not a predictor that you are going to steal a car.
Cheating in person so discreetly that no one is even sure that it happened is the opposite. It would have required custom hardware, discreet placement, and a lot of practice reading the data. Nothing suggests that he was a hardware engineer if any sort. How many accomplices did he have? The more people, the harder to keep a secret.
Similarly, his offers to rematch and play even naked are really doubling down. Magnus seems scared to entertain these matches.