If there was a contract for $280 as you claim then why are they discussing different accounts and amounts instead ? It shows that a deal had not been made yet.
I do think that Bob narrowly escaped being in breach of contract.
I think you are just misinterpreting TECSHARE's point here.
If Bob123 didn't wanted to go into the contract with the seller or if the seller didn't wanted to engage in the contract with Bob123, this telegram discussion you are implying would just not exist.
Bob123 had a pri-decided intention to engage in the contract with the account seller and than again broke it intentionally after exposing his digital goods.
There is also a consistent trend of the seller believing the buyer will not follow through with a sale. It shows that the seller knows that there is a risk of a "no sale".
Yes, there was a risk of no sale before the seller revealed his accounts to Bob123, but when Bob123 agreed to buy the account once the ownership is proved the contract should be automatically formed there after IMO.
I find your way of relating this incident to court judgements interesting, but I don't think we could imply complex court laws here anyways there are too many differences.