Daniel Naroditsky[1] said at the St Louis chess club specifically it would be pretty easy to cheat OTB no matter what searches they do. He said there is a balcony which the players have access to when they walk away from the board which has a clear view of the car park and you could have an assistant signal from there at crucial moments. He also cited a case of a player who was definitely cheating OTB[2] and was never caught and where no mechanism was ever found.
It really seems to me that everyone is overthinking this. Hans has admitted to cheating and just says he didn't cheat here. The idea we should give him the benefit of the doubt seems really odd. It doesn't really matter to me whether he cheated in this specific tournament - he shouldn't have a place in the chess world.
[1] https://www.youtube.com/watch?v=eJVzSXsZ10I&t=3291s
[2] in the sense that every move for an extended period covering multiple tournaments was exactly the top engine move - way more accurate than any human ever
