Legality of hiding cards during Thoughtseize?

My ranting comes from the perspective of someone who has encountered and had to deal with people who I consider to be cheating. The problem with that logic that judges often times use is that the only source for it is the player who probably cheated. So in comp REL, on camera in the future if I "accidentally" do that I can just get away with it, did he even receive a warning? I guess he would have to as the card reads target player reveals his or her hand and he didn't actually complete that action. I just think cases like this are exactly why some people will cheat and be successful in doing so. If this match wasn't on camera / feature match you wouldn't have ever known it happened. People try to cheat like this way too often off camera as well. I find it also a little odd, so he knew a heroes downfall was in his hand, he lays down his cards, at no point does he look down, is he just looking up at the ceiling during the thoughtseize?

I don't know, it's frusturating because I feel like this is another ruling that encourages sketchy behavior that is antithetical to the spirit of how magic should be played. In highly competitive spots IE, I need to win out, or it's a win and in, i've been tempted many times and seriously considered doing things that would be sketchy, and i've only even mildly considered that because I know without a doubt, I wouldn't get punished for it. It's cases like this where the sketchy / cheating action was on camera and they still don't get punished that makes me consider "well if they can get away with it on camera I could certainly do it if I wanted to off camera."

To clarify, I would never cheat... But coming from a poker perspective where a lot of small habits and tendancies are practiced to grind the SLIGHTEST percent of an advantage, the advantage you could gain by playing sketchy and making "mistakes" is actually pretty huge. That downfall in that game was actually pretty huge from a raw % to win perspective. I think had downfall been taken he would have been like ~10% to win, without it he had like 20%+ to win from that spot. Making "mistakes" like that which give a player a huge edge to win that the wouldn't otherwise have shouldn't be casually determined to be mistakes, it's why those "mistakes" keep happening.

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