It is not possible to prove unless the Chess Federation subjects players to cavity search. I don't think the Chess Federation wants to set such an extreme precedent. So, the alternative is to exclude people who have admitted to cheating in the past. That's not wrong or immoral. Cheating is immoral. Losing some privileges goes with the territory and should be expected.
Correct, it is not possible to prove. If Magnus had anything - anything - other than "I felt this way" and "he seems too chill" I would suspect something. Those things could be:
- Hans was walking weird (something in his shoe)
- He was making weird movements
- He was distracted, or similar, indicating he's messing with some device
etc... then sure.
Magnus did not say these things, and that is telling.
What I believe happened is Magnus (someone who has presented a lot of anxiety in the past - see this video: https://www.youtube.com/watch?v=WR-4_ouXUV4 but easy to find other examples) was really nervous that Hans may be cheating, and that impacted Magnus's play (he played a very poor game).
Where is the proof?
There's a reason why things like this are in different categories.
I could have been an alcoholic for years, but I shouldn't be branded as one forever to everyone I meet, etc.. it's just wrong. Totally immoral.