The everybody is a perfect logician part means no one gets it wrong and no one make a guess.
They also don’t say the color of their eyes when they leave. They can just use logic to figure it out.
There are some other problems with this versions wording though. Usually you need to specify that the speaker doesn’t lie.
It’s a govt event that’s invite only so they can kick him out. They can’t prosecute him for what he said or prevent him from saying it elsewhere.
Still a shitty thing to do.