Well, you could, but those terms would be ineffective. Of course, this doesn't help if they succeed to intimidate the victim. But if the victim doesn't pay, there's nothing the scammer can do, because this case would never succeed in court.
Having said that, it might help if the victim complains to the police. Depending on how serious customer protection is taken in the US, this business might be more than merely "unethical".
Enough charge backs and they lose their merchant account.
Most Credit cards users don't realize just how simple it is to run a charge back. It is literally one short phone call.