It is simply immoral to deny any kind of redemption to any person who has ever made a mistake. For a person so ready to cast stones, are you yourself without any sin? Should the errors you once made follow you for the rest of your life?
I'd say people should put up some evidence of Niemann's cheating, how exactly he was receiving information on best possible moves, or just shut up about it. Or dial the anti-cheating measures to eleven, strip the players naked, put them in a Faraday-cage without spectators and cameras, and see how they do.
Do you see how absolutely impossible to do this, don't you?
And honestly, even if it was proposed as a joke, a bluetooth buttplug actually sounds like a good secret channel for small amounts of information if you don't mind it sitting there. You're probably can feel the vibration very well and add some bits with different vibration speeds and patterns. I feel like the shoe method would require you to have your feet still and it's easier to enforce a shoe check than an anal probing...
why would you need proof when Niemann already admitted to cheating in the past?