This is not what happened here.
An acceptance is a final and unqualified expression of assent to the terms of
an offer. Again, there must be an objective manifestation, by the recipient of
the offer, of an intention to be bound by its terms. An offer must be accepted
in accordance with its precise terms if it is to form an agreement. It must
exactly match the offer and ALL terms must be accepted.
Once an offer has been accepted, the parties have an agreement. That is the
basis for a contract, but is not sufficient in itself to create legal obligations.
In common law, a promise is not, as a general rule, binding as a contract
unless it is supported by consideration (or it is made as a deed).
http://www.a4id.org/wp-content/uploads/2016/10/A4ID-english-contract-law-at-a-glance.pdfThis is what happened here.
(i) Breach
3. A breach of contract is committed when a party, without lawful excuse, fails
or refuses to perform what is due from him under the contract, or performs
defectively, or incapacitates himself from performing.
(a) Failure or refusal to perform a failure or refusal to perform a
contractual promise when performance has fallen due is prima facie a
breach.
(b) Defective performance where a person promises to do one thing but
does another, which differs, for example, in time, quantity or quality,
this amounts to a breach. The effect of such a breach often differs
from those of a complete failure or refusal to perform (see below).
Note that where the "defect" in performance is particularly serious, the
breach may amount to non-performance rather than defective
performance (for example, if a seller promises beans but delivers
peas).
(c) Incapacitating oneself for example, a seller commits a breach of
contract for the sale of a specific thing if he sells it to a third party.
http://www.a4id.org/wp-content/uploads/2016/10/A4ID-english-contract-law-at-a-glance.pdfBob123 promised to buy the accounts if the seller releases the details, but after the seller released the details, he just got under defective performance and the contract was breached as he promised one thing and did other. Hence the flag started by the seller is perfectly valid, it's your own judgement if you would like to support it or not but I think a genuine thinking towards the issue would show a serious breach of contract here.