You can participate in transaction. If the business asks you if you want to participate in the transaction, literally no one is stopping you from saying yes.
Basically: I think it would be fine for anyone to participate in market transactions with transparency. But I don’t think there can be transparency here, or that if we really tried then almost no one would accept the transaction anyway.
So I’m thinking a ban of the transactions is the lesser evil.
We already ban e.g sale of your own organs. I’m fine with that too. Now, am I the right person to decide whether people value their kidneys like their integrity? Yes.