8-10 years ago I was watching a weigh-in and they ran a metal detector wand over every fish just for this reason. It doesn’t matter what the endeavor is but if you throw money into it then it’s guaranteed that someone will come up with a way to cheat…unfortunately.
I'm surprised they didn't have those for all the previous tournaments those guys have fished in.
Seems it was SOP for a lot of organizations.
I fished in a bass club down in SoCal for a few years. We were a cool club, had the reputation if anyone needed a beer come find one of our boats. Monthly tournaments. I liked it as it guaranteed I'd get out fishing at least once a month.
Had a guy win big fish of the tournament one month, and ended up with big fish of the year. 12lb 11oz or such.. When he got it back to weigh in it had a 2.5 lb catfish down it's gullet. He caught it on a 4" Shad Rap. Either a reaction bite or that was one hungry fish.
Those guys in the OP should be taken out back and left for the rest of the fishers to deal with for an hour or two.