It's good if it ends up just closing the repeater... Nothing prevents them from just sending a bunch of spam messages to the global channel at some point. After all, the one who pays for a paid repeater, then puts it on to receive global network messages. Usually there is no spam in such a stream, since spammers do not want to pay. But if spammers own a relay, the rules of the game change.
Discussion
But again, the scheme you described is unlikely to be accepted by spammers. It requires costs (advertising relay + time and effort). If they do all this, they are heroes. They will raise a hen laying golden eggs, which it would be strange to kill. Most likely they will be re-educated and stop being spammers. In addition, it is easy for users to disable the relay. If it is closed, the user can accept this fact for himself as a temporary subscription that has ended.