I do  not know any way how they could ban anyone. But it wouldn't be necessary. verifying that a message is false and ignoring it is a really really quick operation.

And Kwothe117, you would not have to send your false guesses to the network. You could just check if your random guess is correct by yourself on your own computer. It would be much faster too.
Then if your random guess is correct you could broadcast it and it will be accepted in to the blockchain...