In my opinion, all the "questionable" training should be done at home, in your own barn. If you go to a show and things go awry, you have to realize that not only are you in a public place with video cameras, you are also in a public place where other children might mimic your behavior, judges might be watching the warm up, etc. etc. If you are not prepared to be able to deal with your horse in a moderately acceptable fashion at a show, you shouldn't be showing. If there is an "emergency", you're going to have to take your chances. But if you are picking big battles in the warm-up pen, it's not going to make much difference.
I think AQHA did a good job of addressing this problem by banning any equipment that is illegal from showing to also be illegal from use in the warm-up pens. Go hanky shank your horses at home, then bring them in. I don't want to see that stuff, I don't care what reason there is.
You wouldn't spank your kids for misbehaving in the middle of a public place, you have to find another way to deal with the problem, or just take the kid/horse out of the situation.