I think their point is there's no "peer to peer" trading so it's not an exchange. You're always contracting futures with them, so it's more like a vegetables seller than a trading facility.
The specific laws do not actually ban the transfer of those contracts (tbf this is very complex and depends on your reading). And yes they do not facilitate the trading of the instruments in the secondary market but they absolutely facilitate the instruments themselves otherwise there cannot be a secondary market without any backers of the instruments.