These are the only ones that are proven to be up for sale, but only to the extent the PMs can be proven.
I do think it is unethical to tell him that you
will trade with him after he provides information, and after receiving information, you do not trade with him "prove the second, then we can do it", and to say that you will pay for something, and subsequently not pay "I pay 350 if it's good" "I pay 550 for green trust legendary ok". It also looks like you entered into a contract with the person, but it does not appear you followed through: "Ok send me message from this acc and we have deal", responding to
https://bitcointalk.org/index.php?action=profile;u=167659 that is a "green trust hero member" to which you agreed to pay 550 for. I don't see evidence you paid him.
If this person were to open up a written contract flag against you, it would be valid.
It wouldn't. Alice/bob didn't agree to pay for merely disclosing the account names, and that's all that happened. He offered to pay for an account, which he didn't end up getting.
According to your "logic" any kind of price/deal negotiation would be a flaggable breach of contract, which is of course utter nonsense. If I say "I'll pay $50 for your bicycle" and change my mind upon seeing said bicycle I'm not breaching your imaginary contract.